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Document And Entity Information - USD ($) $ in Billions	12 Months Ended
Document And Entity Information - USD ($) $ in Billions	Dec. 31, 2011	Feb. 15, 2012	Jun. 30, 2011
Document And Entity Information [Abstract]
Entity Registrant Name	ARCH COAL INC
Entity Central Index Key	0001037676
Document Type	10-K
Document Period End Date	Dec. 31, 2011
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	FY
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 5.6
Entity Common Stock, Shares Outstanding		213,292,678

Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Consolidated Statements Of Income [Abstract]
REVENUES	$ 1,228,756	$ 1,198,673	$ 985,528	$ 872,938	$ 835,394	$ 874,705	$ 764,295	$ 711,874	$ 4,285,895	$ 3,186,268	$ 2,576,081
COSTS, EXPENSES AND OTHER
Cost of sales									3,267,910	2,395,812	2,070,715
Depreciation, depletion and amortization									466,587	365,066	301,608
Amortization of acquired sales contracts, net									(22,069)	35,606	19,623
Selling, general and administrative expenses									119,056	118,177	97,787
Change in fair value of coal derivatives and coal trading activities, net									(2,907)	8,924	(12,056)
Acquisition and transition costs									54,676
Gain on Knight Hawk transaction							(41,600)			(41,577)
Other operating income, net									(10,934)	(19,724)	(39,036)
Total operating expenses									3,872,319	2,862,284	2,452,367
Income from operations	139,728	76,256	95,354	102,238	86,938	98,347	106,499	32,200	413,576	323,984	123,714
Interest expense, net:
Interest expense									(230,186)	(142,549)	(105,932)
Interest income									3,309	2,449	7,622
Interest expense, net									(226,877)	(140,100)	(98,310)
Other non-operating expense:
Bridge financing costs related to ICG									(49,490)
Net loss resulting from early retirement of debt									(1,958)	(6,776)
Other non-operating expense, Total									(51,448)	(6,776)
Income before income taxes									135,251	177,108	25,404
Provision for (benefit from) income taxes									(7,589)	17,714	(16,775)
Net income	$ 71,215	$ 9,121	$ 6,630	$ 55,874	$ 48,031	$ 46,859	$ 66,274	$ (1,770)	142,840	159,394	42,179
Less: Net income attributable to noncontrolling interest									(1,157)	(537)	(10)
Net income attributable to Arch Coal, Inc.									$ 141,683	$ 158,857	$ 42,169
EARNINGS PER COMMON SHARE
Basic earnings per common share	$ 0.34	$ 0.04	$ 0.04	$ 0.34	$ 0.29	$ 0.29	$ 0.41	$ (0.01)	$ 0.75	$ 0.98	$ 0.28
Diluted earnings per common share	$ 0.33	$ 0.04	$ 0.04	$ 0.34	$ 0.29	$ 0.29	$ 0.41	$ (0.01)	$ 0.74	$ 0.97	$ 0.28
Basic weighted average shares outstanding									190,086	162,398	150,963
Diluted weighted average shares outstanding									190,905	163,210	151,272
Dividends declared per common share									$ 0.43	$ 0.39	$ 0.36

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2011	Dec. 31, 2010
Current assets:
Cash and cash equivalents	$ 138,149	$ 93,593
Restricted cash	10,322
Trade accounts receivable	380,595	208,060
Other receivables	88,584	44,260
Inventories	377,490	235,616
Prepaid royalties	21,944	33,932
Deferred income taxes	42,051
Coal derivative assets	13,335	15,191
Other	110,304	104,262
Total current assets	1,182,774	734,914
Property, plant and equipment:
Coal lands and mineral rights	6,578,430	2,523,172
Plant and equipment	3,225,985	2,397,444
Deferred mine development	1,064,279	872,329
Property, plant and equipment	10,868,694	5,792,945
Less accumulated depreciation, depletion and amortization	(2,919,544)	(2,484,053)
Property, plant and equipment, net	7,949,150	3,308,892
Other assets:
Prepaid royalties	86,626	66,525
Goodwill	596,103	114,963
Deferred income taxes	(976,753)	361,556
Equity investments	225,605	177,451
Other	173,701	116,468
Total other assets	1,082,035	836,963
Total assets	10,213,959	4,880,769
Current liabilities:
Accounts payable	383,782	198,216
Coal derivative liabilities	7,828	4,947
Deferred income taxes	(42,051)	7,775
Accrued expenses and other current liabilities	348,207	245,411
Current maturities of debt and short-term borrowings	280,851	70,997
Total current liabilities	1,020,668	527,346
Long-term debt	3,762,297	1,538,744
Asset retirement obligations	446,784	334,257
Accrued pension benefits	48,244	49,154
Accrued postretirement benefits other than pension	42,309	37,793
Accrued workers' compensation	71,948	35,290
Deferred income taxes	976,753
Other noncurrent liabilities	255,382	110,234
Total liabilities	6,624,385	2,632,818
Redeemable noncontrolling interest	11,534	10,444
Stockholders' equity:
Common stock, $0.01 par value, authorized 260,000 shares, issued 213,183 and 164,117 shares at December 31, 2011 and 2010, respectively	2,136	1,645
Paid-in capital	3,015,349	1,734,709
Treasury stock, 1,512 shares at December 31, 2011 and 2010, at cost	(53,848)	(53,848)
Retained earnings	622,353	561,418
Accumulated other comprehensive loss	(7,950)	(6,417)
Total stockholders' equity	3,578,040	2,237,507
Total liabilities and stockholders' equity	$ 10,213,959	$ 4,880,769

Consolidated Balance Sheets (Parenthetical) - $ / shares shares in Thousands	Dec. 31, 2011	Dec. 31, 2010
Stockholders' equity:
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	260,000	260,000
Additional common stock, shares issued	213,183	164,117
Treasury stock, shares	1,512	1,512

Consolidated Statements Of Stockholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Paid-In Capital [Member]	Treasury Stock, At Cost [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Total
BALANCE at Dec. 31, 2008	$ 1,447	$ 1,381,496	$ (53,848)	$ 478,734	$ (79,096)	$ 1,728,733
Comprehensive income:
Net income attributable to Arch Coal, Inc.				42,169		42,169
Pension, postretirement and other post-employment benefits					12,176	12,176
Net amount reclassified to income					718	718
Unrealized gains (losses) on available-for- sale securities					(86)	(86)
Unrealized gains (losses) on derivatives					2,436	2,436
Net amount reclassified to income					43,999	43,999
Total comprehensive income						101,412
Dividends:
Dividends on common shares ($0.36, 0.39 and 0.43 per share for the years 2009, 2010 and 2011 respectively)						(54,969)
Issuance of common shares (19,550 and 48,705 in 2009 and 2011 respectively)	196	326,256				326,452
Issuance of 45, 9 and 162 shares of common stock for the years 2009, 2010 and 2011 respectively under the stock incentive plan - restricted stock and restricted stock units, net of forfeitures	0	0				0
Issuance of 13, 155 and 199 shares of common stock for the years 2009, 2010 and 2011 respectively under the stock incentive plan - stock options including income tax benefits	0	84				84
Employee stock-based compensation expense		13,394				13,394
BALANCE at Dec. 31, 2009	1,643	1,721,230	(53,848)	465,934	(19,853)	2,115,106
Comprehensive income:
Net income attributable to Arch Coal, Inc.				158,857		158,857
Pension, postretirement and other post-employment benefits					9,750	9,750
Net amount reclassified to income					110	110
Unrealized gains (losses) on available-for- sale securities					1,841	1,841
Unrealized gains (losses) on derivatives					221	221
Net amount reclassified to income					1,514	1,514
Total comprehensive income						172,293
Dividends:
Dividends on common shares ($0.36, 0.39 and 0.43 per share for the years 2009, 2010 and 2011 respectively)				(63,373)		(63,373)
Issuance of 45, 9 and 162 shares of common stock for the years 2009, 2010 and 2011 respectively under the stock incentive plan - restricted stock and restricted stock units, net of forfeitures	0	0				0
Issuance of 13, 155 and 199 shares of common stock for the years 2009, 2010 and 2011 respectively under the stock incentive plan - stock options including income tax benefits	2	1,762				1,764
Employee stock-based compensation expense		11,717				11,717
BALANCE at Dec. 31, 2010	1,645	1,734,709	(53,848)	561,418	(6,417)	2,237,507
Comprehensive income:
Net income attributable to Arch Coal, Inc.				141,683		141,683
Pension, postretirement and other post-employment benefits					4,331	4,331
Net amount reclassified to income					1,672	1,672
Unrealized gains (losses) on available-for- sale securities					114	114
Unrealized gains (losses) on derivatives					2,913	2,913
Net amount reclassified to income					(10,563)	(10,563)
Total comprehensive income						140,150
Dividends:
Dividends on common shares ($0.36, 0.39 and 0.43 per share for the years 2009, 2010 and 2011 respectively)				(80,748)		(80,748)
Issuance of common shares (19,550 and 48,705 in 2009 and 2011 respectively)	487	1,267,446				1,267,933
Issuance of 45, 9 and 162 shares of common stock for the years 2009, 2010 and 2011 respectively under the stock incentive plan - restricted stock and restricted stock units, net of forfeitures	2	(2)				0
Issuance of 13, 155 and 199 shares of common stock for the years 2009, 2010 and 2011 respectively under the stock incentive plan - stock options including income tax benefits	2	2,314				2,316
Employee stock-based compensation expense		10,882				10,882
BALANCE at Dec. 31, 2011	$ 2,136	$ 3,015,349	$ (53,848)	$ 622,353	$ (7,950)	$ 3,578,040

Consolidated Statements Of Stockholders' Equity (Parenthetical) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Common dividends, per share	$ 0.43	$ 0.39	$ 0.36
Stock issued during period, shares, new issues	48,705		19,550
Issuance of shares of common stock under the stock incentive plan - restricted stock and restricted stock units	162	9	45
Issuance of shares of common stock under the stock incentive plan - stock options including income tax benefits	199	155	13
Common Stock [Member]
Stock issued during period, shares, new issues	48,705		19,550
Issuance of shares of common stock under the stock incentive plan - restricted stock and restricted stock units	162	9	45
Issuance of shares of common stock under the stock incentive plan - stock options including income tax benefits	199	155	13
Paid-In Capital [Member]
Stock issued during period, shares, new issues	48,705		19,550
Issuance of shares of common stock under the stock incentive plan - restricted stock and restricted stock units	162	9	45
Issuance of shares of common stock under the stock incentive plan - stock options including income tax benefits	199	155	13
Retained Earnings [Member]
Common dividends, per share	$ 0.43	$ 0.39	$ 0.36

- Definition

Number of shares issued during the period related to Restricted Stock Awards, net of any shares forfeited.

+ References + Details

Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
OPERATING ACTIVITIES
Net income	$ 142,840	$ 159,394	$ 42,179
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation, depletion and amortization	466,587	365,066	301,608
Amortization of acquired sales contracts, net	(22,069)	35,606	19,623
Bridge financing costs related to ICG	49,490
Write down of assets acquired from ICG	7,316
Prepaid royalties expensed	34,842	34,605	29,746
Employee stock-based compensation	10,882	11,717	13,394
Amortization relating to financing activities	14,067	10,398	6,741
Gain on Knight Hawk transaction		(41,577)
Net loss resulting from early retirement of debt	1,958	6,776
Changes in operating assets and liabilities:
Receivables	(74,914)	(7,287)	47,794
Inventories	(50,900)	5,160	(28,518)
Coal derivative assets and liabilities	6,079	9,554	32,266
Accounts payable, accrued expenses and other current liabilities	52,191	87,807	(44,764)
Income tax payable/receivable	(21,759)	(1,364)	2,100
Deferred income taxes	10,519	(12,405)	(34,668)
Asset retirement obligations	3,868	23,997	18,741
Other	11,245	9,700	(23,262)
Cash provided by operating activities	642,242	697,147	382,980
INVESTING ACTIVITIES
Acquisitions of businesses, net of cash acquired	(2,894,339)		(768,819)
Increase in restricted cash	5,167
Capital expenditures	(540,936)	(314,657)	(323,150)
Proceeds from dispositions of property, plant and equipment	25,887	330	825
Additions to prepaid royalties	(29,957)	(27,355)	(26,755)
Purchases of investments and advances to affiliates	(61,909)	(46,185)	(10,925)
Consideration paid related to prior business acquisitions	(829)	(1,262)	(4,767)
Reimbursement of deposits on equipment			3,209
Cash used in investing activities	(3,496,916)	(389,129)	(1,130,382)
FINANCING ACTIVITIES
Proceeds from the issuance of senior notes	2,000,000	500,000	584,784
Proceeds from the issuance of common stock, net	1,267,933		326,452
Payments to retire debt	(605,178)	(505,627)
Net increase (decrease) in borrowings under lines of credit and commercial paper program	424,396	(196,549)	(85,815)
Net proceeds from (payments on) other debt	5,334	82	(2,986)
Debt financing costs	(114,823)	(12,751)	(29,659)
Dividends paid	(80,748)	(63,373)	(54,969)
Issuance of common stock under incentive plans	2,316	1,764	84
Contribution from noncontrolling interest		891
Cash provided by (used in) financing activities	2,899,230	(275,563)	737,891
Increase (decrease) in cash and cash equivalents	44,556	32,455	(9,511)
Cash and cash equivalents, beginning of year	93,593	61,138	70,649
Cash and cash equivalents, end of year	138,149	93,593	61,138
SUPPLEMENTAL CASH FLOW INFORMATION:
Cash paid during the year for interest	213,697	134,866	76,801
Cash paid during the year for income taxes	$ 7,094	$ 36,765	$ 17,482

Accounting Policies	12 Months Ended
Accounting Policies	Dec. 31, 2011
Accounting Policies [Abstract]
Accounting Policies	1. Accounting Policies *Basis of Presentation* The consolidated financial statements include the accounts of Arch Coal, Inc. and its subsidiaries and controlled entities ("the Company"). The Company produces coal from surface and underground mines located throughout the United States for sale to domestic and international customers as steam coal to power plants and industrial facilities and metallurgical coal used in steel production. The Company expanded further into metallurgical coal markets with the acquisition of International Coal Group, Inc. ("ICG") on June 15, 2011, as described in Note 3, "Business Combinations." The Company operates 23 mining complexes in West Virginia, Kentucky, Maryland, Virginia, Illinois, Wyoming, Colorado and Utah. All subsidiaries (except as noted below) are wholly-owned. Intercompany transactions and accounts have been eliminated in consolidation. The Company owns a 99% membership interest in a joint venture named Arch Western Resources, LLC ("Arch Western"), which operates coal mines in Wyoming, Colorado and Utah. The Company also acts as the managing member of Arch Western. *Accounting Pronouncements* There were no accounting pronouncements whose adoption had, or is expected to have, a material impact on the Company's consolidated financial statements. *Accounting Estimates* The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and revenues and expenses in the accompanying consolidated financial statements and the disclosure of contingent assets and liabilities. Actual results could differ from those estimates. *Cash and Cash Equivalents* Cash and cash equivalents are stated at cost. Cash equivalents consist of highly-liquid investments with an original maturity of three months or less when purchased. At December 31, 2011 and 2010, the carrying amounts of cash and cash equivalents approximate their fair value. *Allowance for Uncollectible Receivables* The Company establishes an allowance for uncollectible receivables for the amounts of trade accounts receivable and other receivables that are not expected to be collected, based on past collection history, the economic environment and specified risks identified in the receivables portfolio. Receivables are considered past due if the full payment is not received by the contractual due date. At December 31, 2011 and 2010, there was either no allowance or an insignificant allowance for uncollectible receivables. *Inventories* Coal and supplies inventories are valued at the lower of average cost or market. Coal inventory costs include labor, supplies, equipment costs, transportation costs incurred prior to the transfer of title to customers and operating overhead. The costs of removing overburden, called stripping costs, incurred during the production phase of the mine are considered variable production costs and are included in the cost of the coal extracted during the period the stripping costs are incurred. *Investments and Membership Interests in Joint Ventures* Investments and membership interests in joint ventures are accounted for under the equity method of accounting if the Company has the ability to exercise significant influence, but not control, over the entity. The Company's share of the entity's income is reflected in other operating income, net in the consolidated statements of income. Information about investment activity is provided in Note 8, "Equity Investments and Membership Interests in Joint Ventures." Marketable equity securities held by the Company that do not qualify for equity method accounting are classified as available-for-sale and are recorded at their fair value on the balance sheet. Unrealized gains and losses on these investments are recorded in other comprehensive income. A decline in the value of an investment that is considered other-than-temporary is recognized in income. *Prepaid Royalties* Leased mineral rights are often acquired through royalty payments. When royalty payments represent prepayments recoupable against future production, they are recorded as a prepaid asset, with amounts expected to be recouped within one year classified as current. When the coal is mined under these leases the royalties are recouped and the prepayment is charged to cost of sales. *Acquired Sales Contracts* Coal supply agreements (sales contracts) acquired in a business combination are capitalized at their fair value and amortized over the tons of coal shipped during the term of the contract. The fair value of a sales contract is determined by discounting the cash flows attributable to the difference between the contract price and the prevailing forward prices for the tons under contract at the date of acquisition. See Note 6, "Acquired Sales Contracts" for further information related to the Company's acquired sales contracts. *Exploration Costs* Costs to acquire permits for exploration activities are capitalized. Drilling and other costs related to locating coal deposits and evaluating the economic viability of such deposits are expensed as incurred. *Property, Plant and Equipment* Plant and Equipment Plant and equipment are recorded at cost. Interest costs incurred during the construction period for major asset additions are capitalized. Expenditures that extend the useful lives of existing plant and equipment or increase the productivity of the asset are capitalized. The cost of maintenance and repairs that do not extend the useful life or increase the productivity of the asset are expensed as incurred. Preparation plants and loadouts are depreciated using the units-of-production method over the estimated recoverable reserves, subject to a minimum level of depreciation. Other plant and equipment are depreciated principally using the straight-line method over the estimated useful lives of the assets, limited by the remaining life of the mine. The useful lives of mining equipment, including longwalls, draglines and shovels, range from 5 to 32 years. The useful lives of buildings and leasehold improvements generally range from 10 to 30 years. Deferred Mine Development Costs of developing new mines or significantly expanding the capacity of existing mines are capitalized and amortized using the units-of-production method over the estimated recoverable reserves that are associated with the property being benefited. Costs may include construction permits and licenses; mine design; construction of access roads, shafts, slopes and main entries; and removing overburden to access reserves in a new pit. Additionally, deferred mine development includes the asset cost associated with asset retirement obligations. Coal Lands and Mineral Rights Rights to coal reserves may be acquired directly through governmental or private entities. A significant portion of the Company's coal reserves are controlled through leasing arrangements. The net book value of the Company's leased coal interests was $1.6 billion at December 31, 2011 and 2010. Payments to acquire royalty lease agreements and lease bonus payments are capitalized as a cost of the underlying mineral reserves and depleted over the life of proven and probable reserves. Coal lease rights are depleted using the units-of-production method, and the rights are assumed to have no residual value. Lease agreements are generally long-term in nature (original terms range from 10 to 50 years), and substantially all of the leases contain provisions that allow for automatic extension of the lease term providing certain requirements are met. See Note 2, "Property Transactions" for further disclosures on coal lease agreements. Impairment If facts and circumstances suggest that the carrying value of a long-lived asset or asset group may not be recoverable, the asset or asset group is reviewed for potential impairment. If this review indicates that the carrying amount of the asset will not be recoverable through projected undiscounted cash flows generated by the asset and its related asset group over its remaining life, then an impairment loss is recognized by reducing the carrying value of the asset to its fair value. The Company may, under certain circumstances, idle mining operations in response to market conditions or other factors. Because an idling is not a permanent closure, it is not considered an automatic indicator of impairment. *Goodwill* In a business combination, goodwill represents the excess of the purchase price over the fair value assigned to the net tangible and identifiable intangible assets acquired. The Company tests goodwill for impairment annually as of the beginning of the fourth quarter, or when circumstances indicate a possible impairment may exist. If the results of the testing indicate that the carrying amount of a reporting unit exceeds the fair value of the reporting unit, the fair value of goodwill must be calculated. An impairment loss generally would be recognized when the carrying amount of goodwill exceeds the implied fair value of goodwill, determined by subtracting the fair value of the other assets and liabilities associated with the reporting unit from the total fair value of the reporting unit. The fair value of a reporting unit is determined using a discounted cash flow ("DCF") technique. A number of significant assumptions and estimates are involved in the application of the DCF analysis to forecast operating cash flows, including the discount rate and projections of selling prices and costs to produce. *Deferred Financing Costs* The Company capitalizes costs incurred in connection with new borrowings, the establishment or enhancement of credit facilities and the issuance of debt securities. These costs are amortized as an adjustment to interest expense over the life of the borrowing or term of the credit facility using the interest method. The unamortized balance of deferred financing costs was $90.5 million and $37.6 million at December 31, 2011 and 2010, respectively. Amounts classified as current were $15.8 million and $9.6 million at December 31, 2011 and 2010, respectively. Current amounts are recorded in other current assets and noncurrent amounts are recorded in other assets in the accompanying consolidated balance sheets. *Revenue Recognition* Revenues include sales to customers of coal produced at Company operations and coal purchased from third parties. The Company recognizes revenue at the time risk of loss passes to the customer at contracted amounts. Transportation costs are included in cost of sales and amounts billed by the Company to its customers for transportation are included in revenues. *Other Operating Income, Net* Other operating income, net in the accompanying consolidated statements of income reflects income and expense from sources other than physical coal sales, including: bookouts, the practice of offsetting purchase and sale contracts for shipping convenience purposes, and contract settlements; royalties earned from properties leased to third parties; income from equity investments; gains and losses from dispositions of assets; and realized gains and losses on derivatives that do not qualify for hedge accounting and are not held for trading purposes. *Asset Retirement Obligations* The Company's legal obligations associated with the retirement of long-lived assets are recognized at fair value at the time the obligations are incurred. Accretion expense is recognized through the expected settlement date of the obligation. Obligations are incurred at the time development of a mine commences for underground and surface mines or construction begins for support facilities, refuse areas and slurry ponds. The obligation's fair value is determined using a DCF technique and is based upon permit requirements and various estimates and assumptions that would be used by market participants, including estimates of disturbed acreage, reclamation costs and assumptions regarding equipment productivity. Upon initial recognition of a liability, a corresponding amount is capitalized as part of the carrying value of the related long-lived asset. The Company reviews its asset retirement obligation at least annually and makes necessary adjustments for permit changes as granted by state authorities and for revisions of estimates of the amount and timing of costs. For ongoing operations, adjustments to the liability result in an adjustment to the corresponding asset. For idle operations, adjustments to the liability are recognized as income or expense in the period the adjustment is recorded. Any difference between the recorded obligation and the actual cost of reclamation is recorded in profit or loss in the period the obligation is settled. See additional discussion in Note 14, "Asset Retirement Obligations." *Derivative Instruments* The Company generally utilizes derivative instruments to manage exposures to commodity prices. Additionally, the Company may hold certain coal derivative instruments for trading purposes. Derivative financial instruments are recognized in the balance sheet at fair value. Certain coal contracts may meet the definition of a derivative instrument, but because they provide for the physical purchase or sale of coal in quantities expected to be used or sold by the Company over a reasonable period in the normal course of business, they are not recognized on the balance sheet. Certain derivative instruments are designated as the hedge instrument in a hedging relationship. In a fair value hedge, the Company hedges the risk of changes in the fair value of a firm commitment, typically a fixed-price coal sales contract. Changes in both the hedged firm commitment and the fair value of a derivative used as a hedge instrument in a fair value hedge are recorded in earnings. In a cash flow hedge, the Company hedges the risk of changes in future cash flows related to a forecasted purchase or sale. Changes in the fair value of the derivative instrument used as a hedge instrument in a cash flow hedge are recorded in other comprehensive income. Amounts in other comprehensive income are reclassified to earnings when the hedged transaction affects earnings and are classified in a manner consistent with the transaction being hedged. The Company formally documents the relationships between hedging instruments and the respective hedged items, as well as its risk management objectives for hedge transactions. The Company evaluates the effectiveness of its hedging relationships both at the hedge's inception and on an ongoing basis. Any ineffective portion of the change in fair value of a derivative instrument used as a hedge instrument in a fair value or cash flow hedge is recognized immediately in earnings. The ineffective portion is based on the extent to which exact offset is not achieved between the change in fair value of the hedge instrument and the cumulative change in expected future cash flows on the hedged transaction from inception of the hedge in a cash flow hedge or the change in the fair value. Ineffectiveness was insignificant for the years ended December 31, 2011, 2010 and 2009. See Note 10, "Derivative Instruments" for further disclosures related to the Company's derivative instruments. *Fair Value* Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly hypothetical transaction between market participants at a given measurement date. Valuation techniques used must maximize the use of observable inputs and minimize the use of unobservable inputs. See Note 13, "Fair Values of Financial Instruments" for further disclosures related to the Company's fair value estimates. *Income Taxes* Deferred income taxes are provided for temporary differences arising from differences between the financial statement amount and tax basis of assets and liabilities existing at each balance sheet date using enacted tax rates anticipated to be in effect when the related taxes are expected to be paid or recovered. A valuation allowance is established if it is more likely than not that a deferred tax asset will not be realized. In determining the need for a valuation allowance, the Company considers projected realization of tax benefits based on expected levels of future taxable income, available tax planning strategies and its overall deferred tax position. See Note 12, "Taxes" for further disclosures about income taxes. *Benefit Plans* The Company has non-contributory defined benefit pension plans covering most of its salaried and hourly employees. Benefits are generally based on the employee's age and compensation. The Company also currently provides certain postretirement medical and life insurance coverage for eligible employees. The cost of providing these benefits are determined on an actuarial basis and accrued over the employee's period of active service. The Company recognizes the overfunded or underfunded status of these plans as determined on an actuarial basis on the balance sheet and the changes in the funded status are recognized in other comprehensive income. See Note 16, "Employee Benefit Plans" for additional disclosures relating to these obligations. *Stock-Based Compensation* The compensation cost of all stock-based awards is determined based on the grant-date fair value of the award, and is recognized in income over the requisite service period. The grant-date fair value of option awards is determined using a Black-Scholes option pricing model. Compensation cost for an award with performance conditions is accrued if it is probable that the conditions will be met. See further discussion in Note 18, "Stock Based Compensation and Other Incentive Plans."

Property Transactions	12 Months Ended
Property Transactions	Dec. 31, 2011
Property Transactions [Abstract]
Property Transactions	2. Property Transactions On December 14, 2011, the Company was awarded a federal coal lease for the South Hilight tract in Wyoming for a price of $300.0 million. The bid price will be paid in five equal installments, with the first one made in December 2011. The coal lease will give the Company the right to mine an estimated 222 million tons of coal reserves. The South Hilight tract is contiguous to the Company's Black Thunder mining complex. On November 12, 2009, the Company entered into a lease of coal reserves and other coal resources from Great Northern Properties Limited Partnership in Montana for $73.1 million. On March 18, 2010, the Company was awarded a Montana state coal lease for the Otter Creek tracts for a price of $85.8 million. These two transactions gave the Company the right to mine approximately 1.4 billion tons of coal reserves in the Montana's Otter Creek area. The total of the Company's future lease bonus payments due are $23.4 million in 2012, $83.4 million in 2013, $67.3 million in 2014, $60.0 million in 2015 and $60.0 million in 2016.

- Definition

The entire disclosure for long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale. Examples include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software. This disclosure may include property plant and equipment accounting policies and methodology, a schedule of property, plant and equipment gross, additions, deletions, transfers and other changes, depreciation, depletion and amortization expense, net, accumulated depreciation, depletion and amortization expense and useful lives, income statement disclosures, assets held for sale and public utility disclosures.

+ References + Details

Business Combinations

12 Months Ended

Dec. 31, 2011

Business Combinations [Abstract]

Business Combinations

3. Business Combinations

On June 15, 2011, the Company completed its acquisition of ICG, a leading coal producer, adding 12 mining complexes in Appalachia, one complex in the Illinois Basin and one mine under development in Appalachia, along with other coal reserves not currently in development. The Company acquired all of ICG's outstanding shares of common stock. The acquisition was financed with the proceeds from the Company's sale of common stock and issuance of senior notes. See Note 5, "Debt and Financing Arrangements" and Note 17, "Capital Stock" for further information about these transactions.

The following table summarizes the consideration paid for ICG and the recognized amounts of assets acquired and liabilities assumed at the acquisition date:


	(In millions)
Consideration paid, net of cash acquired	$	2,894.4
Recognized amounts of net tangible and intangible assets acquired and liabilities assumed:
Restricted cash	15.5
Receivables	113.2
Inventories	91.0
Net property, plant and equipment, including mineral rights	4,582.6
Goodwill	480.3
Other assets	35.9
Accounts payable	(86.0		)
Other accrued expenses and current liabilities	(59.1		)
Debt	(604.8		)
Litigation accrual	(108.9		)
Accrued postretirement benefits	(47.7		)
Asset retirement obligation	(112.7		)
Coal supply agreements, net	(91.0		)
Deferred income taxes, net	(1,278.9		)
Other	(35.0		)
Net tangible and intangible assets acquired	$	2,894.4

The Company is awaiting the receipt of the final valuation report from a third party valuation services firm. As a result the fair values for mineral rights, goodwill and deferred taxes may not be final.

The revenues and income before income taxes related to the acquired operations reflected in the consolidated statements of income since the date of acquisition were $606.9 million and $14.6 million, respectively.

The following unaudited pro forma information has been prepared for illustrative purposes and assumes that the business combination occurred on January 1, 2010. The unaudited pro forma results have been prepared based upon ICG's historical results and estimates of the ongoing effects of the transactions that the Company believes are reasonable and supportable. The results are not necessarily reflective of the consolidated results of operations had the acquisition actually occurred on January 1, 2010, nor are they indicative of future operating results.

The unaudited supplemental pro forma financial information of the combined entity follows:


		Year Ended December 31,
		2011				2010
			(In millions)
Total revenues
As reported	$	4,285.9		$	3,186.3
Pro forma	$	4,825.6		$	4,299.9

Net income attributable to Arch Coal
As reported	$	141.7		$	158.9
Pro forma	$	113.5		$	(1.2)

The pro forma income before income taxes includes adjustments to operating costs to reflect the new basis in assets acquired and interest expense to reflect the debt incurred to finance the acquisition. In addition, the following pre-tax costs and expenses reflected in the accompanying consolidated statement of income for the year ended December 31, 2011 are reflected in the pro forma results above as of January 1, 2010.



		(In millions)
Costs of completing the acquisition	$	31.6
Severance costs		15.8
Write off of acquired assets		7.3
Bridge financing fees		49.5
	$	104.2

Severance costs represent both change in control payments to executives and severance for employees terminated after the acquisition. The acquired asset write-off relates to a preparation plant and loadout of an acquired ICG mining operation. The acquired operation was combined with an existing operation of the Company, and utilizes an existing facility.

Synergies from the acquisition are not reflected in the pro forma results.

In conjunction with the acquisition, the Company had $10.3 million of restricted cash at December 31, 2011 to fund change in control payments for executives.

On October 1, 2009 the Company purchased the Jacobs Ranch mining operations for a purchase price of $768.8 million. The acquired operations included approximately 345 million tons of coal reserves. The acquired mining operations were integrated into the Company's Black Thunder mining operations in its Powder River Basin segment. To finance the acquisition, the Company sold shares of its common stock and issued senior notes. See Note 5, "Debt and Financing Arrangements" and Note 17 "Capital Stock" for further information about these transactions.

- Definition

The entire disclosure for a business combination (or series of individually immaterial business combinations) completed during the period, including background, timing, and recognized assets and liabilities. The disclosure may include leverage buyout transactions (as applicable).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Emerging Issues Task Force (EITF)
-Number 88-16
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141
-Paragraph 51, 52
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141R
-Appendix F
-Paragraph F4
-Subparagraph e

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141R
-Paragraph 67-73
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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+ Details

Goodwill

12 Months Ended

Dec. 31, 2011

Goodwill [Abstract]

Goodwill

4. Goodwill

Changes in the carrying value of goodwill for the years ended December 31, 2011, 2010 and 2009 are as follows:

		(In thousands)
Balance at January 1, 2009	$	46,832
Consideration paid related to prior business acquisitions		4,767
Acquisition of Jacobs Ranch		62,102
Balance at December 31, 2009		113,701
Consideration paid related to prior business acquisitions		1,262
Balance at December 31, 2010		114,963
Consideration paid related to prior business acquisitions		829
Acquisition of ICG		480,311
Balance at December 31, 2011	$	596,103

Goodwill of $115.8 million has been allocated to the Company's Powder River Basin segment and goodwill of $480.3 million has allocated to the Company's Appalachia segment, for impairment testing purposes. The goodwill related to the acquisition of ICG is not expected to be deductible for income tax purposes; however, the remaining goodwill is expected to be deductible. The consideration paid related to prior business acquisitions represents ongoing adjustments to the purchase price of a previous acquisition resulting from a 2008 tax settlement.

Debt And Financing Arrangements

12 Months Ended

Dec. 31, 2011

Debt And Financing Arrangements [Abstract]

Debt And Financing Arrangements

5. Debt and Financing Arrangements

Debt consists of the following:


		December 31,
		2011			2010
		(In thousands)
Commercial paper	$		—	$		56,904
Indebtedness to banks under credit facilities			481,300			—
6.75% senior notes ($450.0 million face value) due July 1, 2013			450,971			451,618
8.75% senior notes ($600.0 million face value) due August 1, 2016			588,974			587,126
7.00% senior notes due June 15, 2019 at par			1,000,000			—
7.25% senior notes due October 1, 2020 at par			500,000			500,000
7.25% senior notes due June 15, 2021 at par			1,000,000			—
Other			21,903			14,093
			4,043,148			1,609,741
Less current maturities of debt and short-term borrowings			280,851			70,997
Long-term debt	$		3,762,297	$		1,538,744

The current maturities of debt include contractual maturities, as well as amounts borrowed that are supported by credit facilities that have a term of less than one year and amounts borrowed under credit facilities with terms longer than one year that the Company does not intend to refinance on a long-term basis, based on cash projections and management's plans.

ICG Debt

Upon the closing of the ICG acquisition, the Company gave a 30-day redemption notice to the Trustee of ICG's 9.125% senior notes and legally discharged its obligation under the 9.125% senior notes by depositing $260.7 million with the Trustee to redeem the debt. On July 14, 2011, all of the outstanding 9.125% senior notes were redeemed at an aggregate price of $251.4 million, including the required make-whole premium, plus accrued interest of $5.2 million, and the remainder of the deposit was returned to the Company.

At the acquisition date, ICG's 4.00% convertible senior notes with a fair value of $298.5 million and 9.00% convertible senior notes with a fair value of $1.7 million ("convertible notes") became convertible into cash, pursuant to the amended indentures governing the convertible notes, at a calculated conversion rate of $2,614.6848 for each $1,000 in principal amount surrendered for conversion for the 4.00% convertible notes and $2,392.73414 for the 9.00% convertible notes for conversions occurring prior to August 17, 2011.

At the acquisition date, other ICG debt had a fair value of approximately $54.0 million and consisted mainly of equipment notes and insurance notes payable.

The Company recognized a net loss of $2.0 million during the year ended December 31, 2011 on the early extinguishment of ICG's debt, including the conversions of the 4.00% and 9.00% convertible notes described above. The remaining amounts outstanding under the convertible notes and other ICG debt is included in "other" in the debt table above.

Credit Facilities

On June 14, 2011, the Company amended and restated its secured credit facility to allow for up to $2.0 billion in borrowings. The Company paid and deferred $21.1 million in financing fees related to the amendment of this agreement. Borrowings under this credit facility bear interest at a floating rate based on LIBOR determined by reference to the Company's leverage ratio, as calculated in accordance with the credit agreement. The credit facility has a five-year term that expires on June 14, 2016 and is secured by substantially all of the Company's assets as well as its ownership interests in substantially all of its subsidiaries, excluding its ownership interests in Arch Western and its subsidiaries. Commitment fees of 0.50% per annum are payable on the average unused daily balance of the revolving credit facility. The weighted-average interest rate of the Company's outstanding borrowings under the credit facility was 3.04% at December 31, 2011. Financial covenant requirements may restrict the amount of unused capacity available to the Company for borrowings and letters of credit.

The Company maintains an accounts receivable securitization program under which eligible trade receivables are sold, without recourse, to a multi-seller, asset-backed commercial paper conduit. The entity through which these receivables are sold is consolidated into the Company's financial statements. The Company may borrow and draw letters of credit against the facility, and pays facility fees, program fees and letter of credit fees (based on amounts of outstanding letters of credit) at rates that vary with its leverage ratio, as defined under the program. The Company entered into an amendment to its accounts receivable program in November of 2011 to increase the eligible receivables pool, as defined by the agreement, to include receivables generated from the acquired ICG subsidiaries. On December 13, 2011, the Company entered into another amendment to its accounts receivable securitization program to increase the size of the program to allow for aggregate borrowings and letters of credit of up to $250.0 million from $175.0 million. The total aggregate borrowings and letters of credit are limited by eligible accounts receivable, as defined under the terms of the agreement. The credit facility supporting the borrowings under the program is subject to renewal annually, and expires on December 11, 2012. The interest rate in effect as of December 31, 2011 was 0.73%.

On June 14, 2011, the Company terminated its commercial paper placement program and the supporting credit facility.

The Company's average borrowing level under these programs was approximately $234.2 million and $132.0 million for the years ended December 31, 2011 and 2010, respectively.

Availability

As of December 31, 2011, the Company had $375.0 million of borrowings outstanding under the amended and restated secured credit facility and $106.3 million of borrowings outstanding under its accounts receivable securitization program. The Company also had $146.6 million of outstanding letters of credit at December 31, 2011. As of December 31, 2011, the Company had availability of approximately $901.4 million under all lines of credit, as limited by customary financial covenants that may limit the Company's total debt based on defined earnings measurements.

2013 Senior Notes

The 6.75% senior notes due in 2013 ("2013 Notes") were issued by the Company's subsidiary, Arch Western Finance LLC ("Arch Western Finance"), under an indenture dated June 25, 2003. The Company redeemed $500.0 million aggregate principal amount of the 2013 Notes on September 8, 2010. The Company recongized a loss on the redemption of $6.8 million, including the payment of the $5.6 million redeption premium and the write-off of $3.3 million of unamortized debt financing costs, partially off set by the write-off of $2.1 million of the orgional issue premium. The senior notes are guaranteed by Arch Western and certain of its subsidiaries and are secured by an intercompany notes from Arch Coal, Inc. to Arch Western. The terms of the senior notes contain restrictive covenants that limit Arch Western's ability to, among other things, incur additional debt, sell or transfer assets, and make certain investments. Of the aggregate principal outstanding at December 31, 2011 and 2010, $118.4 million of the 2013 Notes were issued at a premium of 104.75% of par. The premium is amortized over the term of the notes. Interest is payable on the notes on January 1 and July 1 of each year. The notes are redeemable at any time at their face value.

2016 Senior Notes

On July 31, 2009, the Company issued $600.0 million in aggregate principal amount of 8.75% senior unsecured notes due 2016 ("2016 Notes") at an initial issue price of 97.464% of the face amount. The Company incurred issue costs of $14.5 million in association with the 2016 Notes. Interest is payable on the notes on February 1 and August 1 of each year. At any time on or after August 1, 2013, the Company may redeem some or all of the notes. The redemption price, reflected as a percentage of the principal amount, is: 104.375% for notes redeemed between August 1, 2013 and July 31, 2014; 102.188% for notes redeemed between August 1, 2014 and July 31, 2015; and 100% for notes redeemed on or after August 1, 2015. In addition, at any time and on one or more occasions prior to August 1, 2012, the Company may redeem an aggregate principal amount of senior notes not to exceed 35% of the original aggregate principal amount of the senior notes outstanding with the proceeds of one or more public equity offerings, at a redemption price equal to 108.750%.

2020 Senior Notes

On August 9, 2010, we issued $500.0 million in aggregate principal amount of 7.25% senior unsecured notes due in 2020 ("2020 Notes") at par. Interest is payable on the 2020 Notes on April 1 and October 1 of each year. At any time on or after October 1, 2015, the Company may redeem some or all of the notes. The redemption price reflected as a percentage of the principal amount is: 103.625% for notes redeemed between October 1, 2015 and September 30, 2016; 102.417% for notes redeemed between October 1, 2016 and September 30, 2017; 101.208% for notes redeemed between October 1, 2017 and September 30, 2018; and 100% for notes redeemed on or after October 1, 2018. In addition, at any time and on one or more occasions prior to October 1, 2013, the Company may redeem an aggregate principal amount of senior notes not to exceed 35% of the original aggregate principal amount of the senior notes outstanding with the proceeds of one or more public equity offerings, at a redemption price equal to 107.250%.

2019 and 2021 Senior Notes

On June 14, 2011, the Company entered into an indenture in conjunction with the issuance of the 7.00% unsecured senior notes due 2019 ("2019 Notes") and the 7.25% unsecured senior notes due 2021 ("2021 Notes") as discussed in Note 3, "Business Combinations." Interest is payable on the 2019 Notes and 2021 Notes on June 15 and December 15 of each year.

At any time prior to June 15, 2014, the Company may redeem up to 35% of the original aggregate principal amount of each of the 2019 Notes and 2021 Notes, plus accrued and unpaid interest, with the net proceeds from certain equity offerings, at a redemption price, reflected as a percentage of the principal amount, equal to 107.0% and 107.25%, respectively. The Company may redeem the 2019 Notes prior to June 15, 2015 and the 2021 Notes prior to June 15, 2016 at the respective make-whole prices set forth in the indenture. On or after June 15, 2015, the Company may redeem the 2019 Notes for cash at redemption prices, reflected as a percentage of the principal amount, of: 103.5% from June 15, 2015 through June 14, 2016; 101.75% from June 15, 2016 through June 14, 2017; and 100% beginning on June 15, 2017. On or after June 15, 2016, the Company may redeem the 2021 Notes for cash at redemption prices, reflected as a percentage of the principal amount, of: 103.625% from June 15, 2016 through June 14, 2017; 102.417% from June 15, 2017 through June 14, 2018; 101.208% from June 15, 2018 through June 14, 2019 and 100% beginning on June 15, 2019. In each case, accrued and unpaid interest at the redemption date is due upon redemption. Upon a change in control, the Company is required to make a tender offer for both series of notes at a price of 101% of the principal amount. The Company incurred issue costs of $44.2 million related to the issuance of these notes.

The Company and the guarantor subsidiaries entered into a registration rights agreement (the "Registration Rights Agreement") in connection with the issuance and sale of the 2019 Notes and 2021 Notes. Pursuant to the Registration Rights Agreement, the Company and the guarantor subsidiaries agreed to file a registration statement with the Securities and Exchange Commission to register an exchange offer pursuant to which the Company will offer to exchange a like aggregate principal amount of senior notes identical in all material respects to the 2019 Notes and 2021 Notes, except for terms relating to additional interest and transfer restrictions, for any or all of the outstanding 2019 Notes and 2021 Notes. Pursuant to the Registration Rights Agreement, the Company must use commercially reasonable efforts to cause the registration statement to become effective as soon as practicable and to complete the exchange offer no later than June 13, 2012. Should those events not occur within the specified time frame, the applicable interest rates on the 2019 Notes and the 2021 Notes shall be increased by one-quarter of one percent per annum for the first 90 days following the occurrence of such failure. Such interest rate will increase by an additional one-quarter of one percent per annum thereafter at the end of each subsequent 90-day period up to a maximum aggregate increase of one percent per annum. Once any of the required events occur, the interest rates will revert to the rate specified in the indenture governing the 2019 Notes and 2021 Notes.

The 2016, the 2020, the 2019 and the 2021 unsecured senior notes are guaranteed by substantially all of the Company's subsidiaries, including the newly acquired subsidiaries of ICG and excluding Arch Western, its subsidiaries and Arch Receivable Company, LLC and the Company's subsidiaries outside the U.S.

Expected aggregate maturities of debt for the next five years are $280.9 million in 2012, $672.4 in 2013, $0 in 2014, $0 in 2015 and $600.0 million in 2016.

Terms of the Company's credit facilities and leases contain financial and other covenants that limit the ability of the Company to, among other things, acquire, dispose, merge or consolidate assets; incur additional debt; pay dividends and make distributions or repurchase stock; make investments; create liens; issue and sell capital stock of subsidiaries; enter into restrictions affecting the ability of restricted subsidiaries to make distributions, loans or advances to the Company; engage in transactions with affiliates and enter into sale and leaseback transactions. The terms also require the Company to, among other things, maintain various financial ratios and comply with various other financial covenants, including an interest coverage ratio test, as defined in the indentures. In addition, the covenants require the Company to pledge assets to collateralize the revolving credit facility. The assets pledged include equity interests in wholly-owned subsidiaries, certain real property interests, accounts receivable and inventory of the Company. Failure by the Company to comply with such covenants could result in an event of default, which, if not cured or waived, could have a material adverse effect on the Company. The Company complied with all financial covenants at December 31, 2011.

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

+ References + Details

Acquired Sales Contracts

12 Months Ended

Dec. 31, 2011

Acquired Sales Contracts [Abstract]

Acquired Sales Contracts

6. Acquired Sales Contracts

The acquired sales contracts reflected in the condensed consolidated balance sheets are as follows:


		December 31, 2011				December 31, 2010
		Assets		Liabilities		Assets		Liabilities
		(In thousands)				(In thousands)
Acquired fair value	$	149,457	$	166,697	$	114,453	$	40,654
Accumulated amortization		(115,322)		(69,699)		(82,376)		(14,613)
Total	$	34,135	$	96,998	$	32,077	$	26,041
Net total			$	(62,863)	$	6,036
Balance Sheet classification:
Other current	$	18,929	$	38,441	$	25,063	$	5,615
Other noncurrent	$	15,206	$	58,557	$	7,014	$	20,426

Above-market contracts with a fair value of $35.0 million and below-market contracts with a fair value of $126.0 million were acquired from ICG. See Note 3, "Business Combinations" for discussion of purchase price adjustments.

The Company anticipates amortization income of all acquired sales contracts, based upon expected shipments in the next five years, to be approximately $18.5 million in 2012, $5.2 million in 2013, $3.3 million in 2014, $12.7 million in 2015 and $7.7 million in 2016.

Accumulated Other Comprehensive Income (Loss)

12 Months Ended

Dec. 31, 2011

Accumulated Other Comprehensive Income (Loss) [Abstract]

Accumulated Other Comprehensive Income (Loss)

7. Accumulated Other Comprehensive Income (Loss)

Other comprehensive income (loss) includes transactions recorded in stockholders' equity during the year, excluding net income and transactions with stockholders. Following are the items included in accumulated other comprehensive income (loss):

	Derivative Instruments	Pension, Postretirement and Other Post- Employment Benefits	Available-for- Sale Securities	Accumulated Other Comprehensive Loss
	(In thousands)
Balance at January 1, 2009	$ (45,249)	$ (33,433)	$ (414)	$ (79,096)
2009 activity, before tax	72,553	20,124	(136)	92,541
2009 activity, tax effect	(26,118)	(7,230)	50	(33,298)
Balance at December 31, 2009	1,186	(20,539)	(500)	(19,853)
2010 activity, before tax	2,711	15,406	2,877	20,994
2010 activity, tax effect	(976)	(5,546)	(1,036)	(7,558)
Balance at December 31, 2010	2,921	(10,679)	1,341	(6,417)
2011 activity, before tax	(11,951)	9,345	176	(2,430)
2011 activity, tax effect	4,301	(3,342)	(62)	897
Balance at December 31, 2011	$ (4,729)	$ (4,676)	$ 1,455	$ (7,950)

- Definition

The entire disclosure for comprehensive income. Includes, but is not limited to, the following: 1) the amount of income tax expense or benefit allocated to each component of other comprehensive income, including reclassification adjustments, 2) the reclassification adjustments for each classification of other comprehensive income and 3) the ending accumulated balances for each component of comprehensive income. Components of comprehensive income include: (1) foreign currency translation adjustments; (2) gains (losses) on foreign currency transactions that are designated as, and are effective as, economic hedges of a net investment in a foreign entity; (3) gains (losses) on intercompany foreign currency transactions that are of a long-term-investment nature, when the entities to the transaction are consolidated, combined, or accounted for by the equity method in the reporting enterprise's financial statements; (4) change in the market value of a futures contract that qualifies as a hedge of an asset reported at fair value; (5) unrealized holding gains (losses) on available-for-sale securities and that resulting from transfers of debt securities from the held-to-maturity category to the available-for-sale category; (6) a net loss recognized as an additional pension liability not yet recognized as net periodic pension cost; and (7) the net gain (loss) and net prior service cost or credit for pension plans and other postretirement benefit plans.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 130
-Paragraph 14-26
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=6920043&loc=d3e637-108580

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14
-URI http://asc.fasb.org/extlink&oid=6920043&loc=d3e681-108580

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=6920043&loc=d3e653-108580

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=6959260&loc=d3e187085-122770

Reference 6: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-Paragraph 16
-URI http://asc.fasb.org/extlink&oid=6920043&loc=d3e709-108580

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 55
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6920433&loc=d3e998-108581

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
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-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=6920043&loc=d3e640-108580

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Reclassification Adjustments
-URI http://asc.fasb.org/extlink&oid=6522872

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=6920043&loc=d3e716-108580

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=6920043&loc=d3e689-108580

+ Details

Equity Investments And Membership Interests In Joint Ventures

12 Months Ended

Dec. 31, 2011

Equity Investments And Membership Interests In Joint Ventures [Abstract]

Equity Investments And Membership Interests In Joint Ventures

8. Equity Investments and Membership Interests in Joint Ventures

Below are the equity method investments reflected in the consolidated balance sheets:

	Knight Hawk	DKRW	DTA	Tenaska	Millennium	Tongue River	Total
	(In thousands)

Balance at January 1 , 2009	$ 48,093	$ 25,124	$ 14,544	$ —	$ —	$ —	$ 87,761
Advances to (distributions from) affiliates, net	(5,164)	—	2,925	—	—	—	(2,239)
Equity in comprehensive income (loss)	6,674	(1,535)	(3,393)	—	—	—	1,746
Balance at December 31, 2009	49,603	23,589	14,076	—	—	—	87,268
Investments in affiliates	77,637	—	—	9,768	—	—	87,405
Advances to (distributions from) affiliates, net	(12,639)	—	4,264	—	—	—	(8,375)
Equity in comprehensive income (loss)	16,649	(1,628)	(3,868)	—	—	—	11,153
Balance at December 31, 2010	$ 131,250	$ 21,961	$ 14,472	$ 9,768	$ —	$ —	$ 177,451
Investments in affiliates	—	—	—	5,500	25,000	12,989	43,489
Advances to (distributions from) affiliates, net	(16,621)	—	6,498	—	3,477	—	(6,646)
Equity in comprehensive income (loss)	20,596	(2,246)	(4,884)	(2)	(2,153)	—	11,311
Balance at December 31, 2011	$ 135,225	$ 19,715	$ 16,086	$ 15,266	$ 26,324	$ 12,989	$ 225,605
Notes receivable from investees:
Balance at December 31, 2010	$ 1,700	$ 18,100	$ —	$ 4,100	$ —	$ —	$ 23,900
Balance at December 31, 2011	—	30,751	—	5,059	—	—	35,810

The Company holds an equity interest in Knight Hawk Holdings, LLC ("Knight Hawk"), a coal producer in the Illinois Basin. In June 2010, the Company exchanged 68.4 million tons of coal reserves in the Illinois Basin for an additional 9% ownership interest, increasing the Company's ownership in Knight Hawk to 42% from 33 1/3%. The Company recognized a gain of $41.6 million on the transaction, representing the difference between the fair value and the $12.1 million net book value of the coal reserves, adjusted for the Company's retained ownership interest in the reserves through its investment in Knight Hawk. In December 2010, the Company increased its ownership interest in Knight Hawk to 49% for $26.6 million in cash.

The Company holds a 24% equity interest in DKRW Advanced Fuels LLC ("DKRW"), a company engaged in developing coal-to-liquids facilities. Under a coal reserve purchase option with DKRW, DKRW could purchase reserves from the Company, which the Company would then mine on a contract basis for DKRW. DKRW may borrow funds from the Company under a convertible secured promissory note. Amounts borrowed are due and payable in cash or in additional equity interests on the earlier of April 15, 2012 or upon the closing of DKRW's next financing, bear interest at the rate of 1.25% per month, and are secured by DKRW's equity interests in Medicine Bow Fuel & Power LLC. As of December 31, 2011, DKRW had borrowed the maximum amount allowed under the note. The note balances above are reflected in other receivables on the consolidated balance sheets.

The Company holds a general partnership interest of 21.875% in Dominion Terminal Associates ("DTA"), which is accounted for under the equity method. DTA operates a ground storage-to-vessel coal transloading facility in Newport News, Virginia for use by the partners. Under the terms of a throughput and handling agreement with DTA, each partner is charged its share of cash operating and debt-service costs in exchange for the right to use the facility's loading capacity and is required to make periodic cash advances to DTA to fund such costs.

The Company holds a 35% ownership interest in Tenaska Trailblazer Partners, LLC ("Tenaska"), the developer of the Trailblazer Energy Center, a fossil-fuel-based electric power plant near Sweetwater, Texas. The plant, fueled by low sulfur coal, will capture and store carbon dioxide for enhanced oil recovery applications. Additional future payments are due upon the achievement of project milestones to maintain the Company's interest. The Company made a milestone payment of $5.5 million in 2011. The Company will also pay 35% of the future development costs of the project, not to exceed $12.5 million without prior approval from the Company. The receivables for these development costs, shown above, are reflected in the consolidated balance sheets in other noncurrent assets, as the development costs will either be reimbursed when the project receives construction financing, or they will be considered an additional capital contribution, with ownership percentages adjusted accordingly.

In January 2011, the Company purchased a 38% ownership interest in Millennium Bulk Terminals-Longview, LLC ("Millennium"), the owner of a brownfield bulk commodity terminal on the Columbia River near Longview, Washington, for $25.0 million, plus additional future consideration upon the completion of certain project milestones. Millennium continues to work on obtaining the required approvals and necessary permits to complete dredging and other upgrades to enable coal, alumina and cementitious material shipments through the terminal. The Company will control 38% of the terminal's throughput and storage capacity, in order to facilitate export shipments of coal off the west coast of the United States.

In July 2011, the Company purchased a 33% membership interest in the Tongue River Holding Company, LLC ("Tongue River") joint venture. Tongue River will develop and construct a railway line near Miles City, Montana and the Company's Otter Creek reserves. The Company has the right, upon the receipt of permits and approval for construction or under other prescribed circumstances, to require the other investors to purchase all of the Company's units in the venture at an amount equal to the capital contributions made by the Company at that time, less any distributions received.

Under development financing agreements with certain investees, the Company may be required to make future contingent payments of up to $74.4 million, including milestone payments. The Company's obligation to make these payments, as well as the timing of any payments required, is contingent upon a number of factors, including project development progress, receipt of permits and construction financing.

Summarized financial information of the Company's equity method investees follows:


	December 31
	2011	2010	2009
Condensed combined income statement information:	(In thousands)
Revenues	$ 184,358	$ 172,933	$ 166,152
Gross profit	19,495	25,203	15,426
Income from operations	13,180	20,243	1,611
Net income (loss)	6,788	16,015	(1,797)

Condensed combined balance sheet information:
Current assets	$ 94,644	$ 48,202
Noncurrent assets	331,848	276,125
Total assets	$ 426,492	$ 324,327
Current liabilities	$ 51,674	$ 39,237
Noncurrent liabilities	120,494	99,350
Equity	254,163	185,639
Noncontrolling interest	161	101
Total liabilities and equity	$ 426,492	$ 324,327

- Definition

The entire disclosure for equity investment, or group of investments, for which combined disclosure is appropriate, including: (a) the name of each investee and percentage of ownership of common stock, (b) accounting policies for investments in common stock, (c) difference between the amount at which the investment is carried and the amount of underlying equity in net assets and the accounting treatment of the difference, (d) the total fair value of each identified investment for which a market value is available, (e) summarized information as to assets, liabilities, and results of operations of the investees (for investments in unconsolidated subsidiaries, common stock of joint ventures, or other investments using the equity method), and (f) material effects of possible conversions, exercises, or contingent issuances of the investee. Other disclosures include (a) the names of any investee in which the investor owns 20 percent or more of the voting stock and investment is not accounted for using the equity method, and the reasons why not, and (b) the names of any investee in which the investor owns less than 20 percent of the voting stock and the investment is accounted for using the equity method, and the reasons why it is.

+ References + Details

Inventories

12 Months Ended

Dec. 31, 2011

Inventories [Abstract]

Inventories

9. Inventories

Inventories consist of the following:


	December 31
	2011	2010
	(In thousands)
Coal	$ 206,517	$ 115,647
Repair parts and supplies	163,527	119,969
Work-in-process	7,446	—
	$ 377,490	$ 235,616

The work-in-process is related the Company's ADDCAR subsidiary acquired with ICG, which manufactures and sells its patented highwall mining system. The repair parts and supplies are stated net of an allowance for slow-moving and obsolete inventories of $13.1 million and $12.7 million at December 31, 2011 and 2010, respectively.

Derivative Instruments

12 Months Ended

Dec. 31, 2011

Derivative Instruments [Abstract]

Derivative Instruments

10. Derivative Instruments

Diesel fuel price risk management

The Company is exposed to price risk with respect to diesel fuel purchased for use in its operations. The Company anticipates purchasing approximately 80 to 90 million gallons of diesel fuel for use in its operations during 2012. To reduce the volatility in the price of diesel fuel for its operations, the Company uses forward physical diesel purchase contracts, as well as heating oil swaps and purchased call options. At December 31, 2011, the Company had protected the price of approximately 82% of its expected purchases for fiscal year 2012.

At December 31 2011, the Company held heating oil swaps and purchased call options for approximately 69 million gallons for the purpose of managing the price risk associated with future diesel purchases. Since the changes in the price of heating oil highly correlate to changes in the price of the hedged diesel fuel purchases, the heating oil swaps and purchased call options qualify for cash flow hedge accounting.

The Company also purchased heating oil call options to hedge the fuel surcharges on its barge and rail shipments that cover increases in diesel fuel prices. These positions reduce the Company's risk of cash flow fluctuations related to these surcharges but the positions are not accounted for as hedges. At December 31, 2011, Company held purchased call options for approximately 19.1 million gallons for the purpose of managing the fluctuations in cash flows associated with fuel surcharges on future shipments.

Coal risk management positions

The Company may sell or purchase forward contracts, swaps and options in the over-the-counter coal market in order to manage its exposure to coal prices. The Company has exposure to the risk of fluctuating coal prices related to forecasted sales or purchases of coal or to the risk of changes in the fair value of a fixed price physical sales contract. Certain derivative contracts may be designated as hedges of these risks.

At December 31, 2011, the Company held derivatives for risk management purposes that are expected to settle in the following years :



	2012	2013	2014	2015
(Tons in thousands)
Coal sales	2,416	1,117	1,440	720
Coal purchases	254	—	—	—

Coal trading positions

The Company may sell or purchase forward contracts, swaps and options in the over-the-counter coal market for trading purposes. The Company is exposed to the risk of changes in coal prices on the value of its coal trading portfolio. The estimated future realization of the value of the trading portfolio is $2.6 million of losses in 2012 and $1.8 million of losses in 2013.

Tabular derivatives disclosures

The Company's contracts with certain of its counterparties allow for the settlement of contracts in an asset position with contracts in a liability position in the event of default or termination. Such netting arrangements reduce the Company's credit exposure related to these counterparties. For classification purposes, the Company records the net fair value of all the positions with a given counterparty as a net asset or liability in the consolidated balance sheets. The amounts shown in the table below represent the fair value position of individual contracts, regardless of the net position presented in the accompanying consolidated balance sheets. The fair value and location of derivatives reflected in the accompanying consolidated balance sheets are as follows:

Fair Value of Derivatives

(In thousands)


	December 31, 2011								December 31, 2010
	Asset Derivative			Liability Derivative					Asset Derivative			Liability Derivative
Derivatives Designated as Hedging Instruments
Heating oil – diesel purchases	$	8,997		$	—				$	13,475		$	—
Coal	1,109			—					2,009			(2,350		)
Total	10,106			—					15,484			(2,350		)
Derivatives Not Designated as Hedging Instruments
Heating oil – fuel surcharges	1,797			—					—			—
Coal — held for trading purposes	15,505			(19,927		)			34,445			(24,087		)
Coal	14,855			(6,035		)			1,139			(912		)
Total	32,157			(25,962		)			35,584			(24,999		)
Total derivatives	42,263			(25,962		)			51,068			(27,349		)
Effect of counterparty netting	(18,134		)	18,134					(22,402		)	22,402
Net derivatives as classified in the balance sheets	$	24,129		$	(7,828	)	$	16,301	$	28,666		$	(4,947	)	$	23,719

Net derivatives as reflected on the balance sheets


		December 31, 2011			December 31, 2010
Heating oil	Other current assets	$	10,794		$	13,475
Coal	Coal derivative assets	13,335			15,191
	Coal derivative liabilities	(7,828		)	(4,947		)
		$	16,301		$	23,719

The Company had a current asset for the right to reclaim cash collateral of $12.4 million and $10.3 million at December 31, 2011 and December 31, 2010, respectively. These amounts are not included with the derivatives presented in the table above and are included in "other current assets" in the accompanying consolidated balance sheets.

The effects of derivatives on measures of financial performance are as follows:

Year Ended December 31,

(In thousands)

Derivatives used in

Fair Value Hedging

Gain on Derivatives Used in

Hedged Items in

Fair Value Hedge

Loss on Hedged Items In Fair Value

Relationships

Fair Value Hedge Relationships

Relationships

Hedge Relationships

2011

2010

2009

2011

2010

2009

(In thousands)

Coal

$ —

(3)

$ —

(3)

$ 2,586

(3)

Firm commitments

$ —

(3)

$ —

(3)

$ (2,586)

(3)


Derivatives used in Cash Flow Hedging	Gain (Loss) Recognized in OCI (Effective Portion)										Gains (Losses) Reclassified from OCI into Income (Effective Portion)
Relationships	2011			2010			2009			2011				2010			2009
Heating oil – diesel purchases	$	1,294		$	(149	)	$	10,309		$		14,866	(2)	$	437	(2)	$	(49,055	)	(2)
Coal sales	4,923			(4,714		)	(7,441		)	1,572			(1)	(1,602)		(1)	(6,999		)	(1)
Coal purchases	(2,009		)	5,145			1,089			—			(2)	(1,202)		(2)	(13,181		)	(2)
Totals	$	4,208		$	282		$	3,957		$		16,438		$	(2,367	)	$	(69,235)


Derivatives used in Cash Flow Hedging	Gain (Loss) Recognized in Income (Ineffective Portion and Amount Excluded from Effectiveness Testing)
Relationships	2011		2010		2009
Heating oil – diesel purchases	$	—	$	—	$ —
Coal sales	—		—		—
Coal purchases	—		—		—
Totals	$	—	$	—	$	—


Derivatives Not Designated as	Gain (Loss)
Hedging Instruments	2011			2010			2009
Coal — unrealized	$	6,438	(3)	$	(10,991)	(3)	$ 9,673	(3)
Coal — realized	$	(7)	(4)	$	4,542	(4)	$ —	(4)
Heating oil — fuel surcharges — unrealized	$	(2,906)	(4)	$	—	(4)	$ —	(4)

Location in Statement of Income:

(1) Revenues

(2) Cost of sales

(3) Change in fair value of coal derivatives and coal trading activities, net

(4) Other operating income, net

The Company recognized net unrealized and realized losses of $3.5 million during the year ended December 31, 2011 and net unrealized and realized gains of $2.1 million and $2.4 million, during the years ended December 31, 2010 and 2009, respectively, related to its trading portfolio (including derivative and non-derivative contracts). These balances are included in the caption "Change in fair value of coal derivatives and coal trading activities, net" in the accompanying consolidated statements of income and are not included in the previous table.

During the next twelve months, based on fair values at December 31, 2011, gains on derivative contracts designated as hedge instruments in cash flow hedges of approximately $9.2 million are expected to be reclassified from other comprehensive income into earnings.

- Definition

The entire disclosure for the entity's entire derivative instruments and hedging activities. Describes an entity's risk management strategies, derivatives in hedging activities and non-hedging derivative instruments, the assets, obligations, liabilities, revenues and expenses arising therefrom, and the amounts of and methodologies and assumptions used in determining the amounts of such items.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 45
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 44
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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+ Details

Accrued Expenses And Other Current Liabilities

12 Months Ended

Dec. 31, 2011

Accrued Expenses And Other Current Liabilities [Abstract]

Accrued Expenses And Other Current Liabilities

11. Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consist of the following:


		December 31
	2011		2010
		(In thousands)
Payroll and employee benefits	$	65,323	$	51,327
Taxes other than income taxes		133,331		107,969
Interest		55,266		52,843
Acquired sales contracts (see Note 6)		38,441		5,615
Workers' compensation (see Note 15)		11,666		6,659
Asset retirement obligations (see Note 14)		27,119		8,862
Other		17,061		12,136
	$	348,207	$	245,411

Taxes

12 Months Ended

Dec. 31, 2011

Taxes [Abstract]

Taxes

12. Taxes

The Company is subject to U.S. federal income tax as well as income tax in multiple state jurisdictions. The tax years 2005 through 2011 remain open to examination for U.S. federal income tax matters and 1998 through 2011 remain open to examination for various state income tax matters.

Significant components of the provision for (benefit from) income taxes are as follows:


	Year Ended December 31
	2011	2010	2009
	(In thousands)
Current:
Federal	$ (20,164)	$ 34,304	$ 21,295
State	1,212	2,283	864
Total current	(18,952)	36,587	22,159
Deferred:
Federal	13,214	(18,506)	(39,492)
State	(1,851)	(367)	558
Total deferred	11,363	(18,873)	(38,934)
	$ (7,589)	$ 17,714	$ (16,775)

A reconciliation of the statutory federal income tax expense on the Company's pretax income to the actual provision for (benefit from) income taxes follows:


	Year Ended December 31
	2011	2010	2009
	(In thousands)
Income tax expense at statutory rate	$ 46,933	$ 61,800	$ 8,888
Percentage depletion allowance	(61,971)	(49,152)	(29,463)
State taxes, net of effect of federal taxes	(3,055)	2,299	(61)
Change in valuation allowance	2,416	(383)	725
Other, net	8,088	3,150	3,136
	$ (7,589)	$ 17,714	$ (16,775)

In 2011, 2010 and 2009, compensatory stock options and other equity based compensation awards were exercised resulting in a tax expense (benefit) of $(0.4) million, $(0.8) million and $0.2 million, respectively. The tax benefit will be recorded in paid-in capital at such point in time when a cash tax benefit is recognized.

Significant components of the Company's deferred tax assets and liabilities that result from carryforwards and temporary differences between the financial statement basis and tax basis of assets and liabilities are summarized as follows:


	December 31
	2011	2010
	(In thousands)
Deferred tax assets:
Alternative minimum tax credit carryforwards	$ 151,404	$ 170,592
Net operating loss carryforwards	324,393	102,355
Reclamation and mine closure	93,914	71,533
Advance royalties	—	38,557
Plant and equipment	—	19,846
Acquired sales contracts	44,717	20,120
Other, primarily accrued liabilities	171,715	90,412
Gross deferred tax assets	786,143	513,415
Valuation allowance	(2,831)	(737)
Total deferred tax assets	783,312	512,678
Deferred tax liabilities
Plant and equipment	1,566,769	—
Deferred development	67,728	76,690
Investment in tax partnerships	66,502	68,538
Other	17,015	13,669
Total deferred tax liabilities	1,718,014	158,897
Net deferred tax asset (liability)	(934,702)	353,781
Current asset (liability)	42,051	(7,775)
Non-current deferred tax asset (liability)	$ (976,753)	$ 361,556

The Company has federal net operating loss carryforwards for regular income tax purposes of $779.1 million at December 31, 2011 that will expire between 2012 and 2031. The Company has an alternative minimum tax credit carryforward of $151.4 million at December 31, 2011, which has no expiration date and can be used to offset future regular tax in excess of the alternative minimum tax.

During 2008, the Company reached a settlement with the IRS regarding the Company's treatment of the acquisition of the coal operations of Atlantic Richfield Company ("ARCO") and the simultaneous combination of the acquired ARCO operations and the Company's Wyoming operations into the Arch Western joint venture. The settlement did not result in a net change in deferred tax assets, but involved a re-characterization of deferred tax assets, including an increase in net operating loss carryforwards of $145.1 million and other amortizable assets which will provide additional tax deductions through 2013. A portion of these future cash tax benefits accrue to ARCO pursuant to the original purchase agreement, including $0.8 million, $1.3 million and $4.8 million paid in 2011, 2010 and 2009, respectively, that was recorded as goodwill.

The Company has recorded a valuation allowance for a portion of its deferred tax assets that management believes, more likely than not, will not be realized. Management reassesses the ability to realize its deferred tax assets annually in the fourth quarter or when circumstances indicate that the ability to realize deferred tax assets has changed. In determining the appropriate valuation allowance, the assessment takes into account expected future taxable income and available tax planning strategies. This review resulted in increases (decreases) in the valuation allowance of $2.1 million, $(0.4) million and $0.7 million in 2011, 2010 and 2009, respectively. The valuation allowance relates to certain state and foreign net operating loss benefits.

A reconciliation of the beginning and ending amounts of gross unrecognized tax benefits is as follows (in thousands):

Balance at January 1, 2009	$ 4,878
Additions based on tax positions related to the current year	1,593
Additions for tax positions of prior years	205
Reductions for tax positions of prior years	(6)
Balance at December 31, 2009	6,670
Additions based on tax positions related to the current year	1,493
Additions for tax positions of prior years	85
Reductions for tax positions of prior years	(3,830)
Balance at December 31, 2010	4,418
Additions based on tax positions related to the current year	1,626
Additions for tax positions of prior years	2,754
Balance at December 31, 2011	$ 8,798

If recognized, the entire amount of the gross unrecognized tax benefits at December 31, 2011 would affect the effective tax rate.

The Company recognizes interest and penalties accrued related to unrecognized tax benefits in income tax expense. The Company had accrued interest and penalties of $0.8 million and $0.6 million at December 31, 2011 and 2010, respectively, of which $0.2 million and $0.1 million was recognized as expense during 2011 and 2010, respectively. No gross unrecognized tax benefits are expected to be reduced in the next 12 months due to the expiration of the statute of limitations.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Paragraph h
-Article 4

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 109
-Paragraph 136, 172
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 109
-Paragraph 43, 44, 45, 46, 47, 48, 49
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32718-109319

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32639-109319

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(h))
-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32537-109319

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32559-109319

+ Details

Fair Value Measurements

12 Months Ended

Dec. 31, 2011

Fair Value Measurements [Abstract]

Fair Value Measurements

13. Fair Value Measurements

The hierarchy of fair value measurements prioritizes the inputs to valuation techniques used to measure fair value. The levels of the hierarchy, as defined below, give the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities and the lowest priority to unobservable inputs.

· Level 1 is defined as observable inputs such as quoted prices in active markets for identical assets. Level 1 assets include available-for-sale equity securities and coal futures that are submitted for clearing on the New York Mercantile Exchange.

· Level 2 is defined as observable inputs other than Level 1 prices. These include quoted prices for similar assets or liabilities in an active market, quoted prices for identical assets and liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. The Company's level 2 assets and liabilities include commodity contracts (coal and heating oil) with fair values derived from quoted prices in over-the-counter markets or from prices received from direct broker quotes.

· Level 3 is defined as unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions. These include the Company's commodity option contracts (primarily coal and heating oil) valued using modeling techniques, such as Black-Scholes, that require the use of inputs, particularly volatility, that are rarely observable.

The table below sets forth, by level, the Company's financial assets and liabilities that are recorded at fair value in the accompanying condensed consolidated balance sheet:


	Fair Value at December 31, 2011
	Total		Level 1		Level 2		Level 3
	(In thousands)
Assets:
Investments in equity securities	$	7,540	$	7,540	$	—	$	—
Derivatives	24,129		12,361		1,450		10,318
Total assets	$	31,669	$	19,901	$	1,450	$	10,318
Liabilities:
Derivatives	$	7,828	$	—	$	3,721	$	4,107

The Company's contracts with certain of its counterparties allow for the settlement of contracts in an asset position with contracts in a liability position in the event of default or termination. For classification purposes, the Company records the net fair value of all the positions with these counterparties as a net asset or liability. Each level in the table above displays the underlying contracts according to their classification in the accompanying condensed consolidated balance sheet, based on this counterparty netting.

The following table summarizes the change in the fair values of financial instruments categorized as level 3.


		Year Ended December 31, 2011
	(In thousands)
Balance, beginning of period		$	9,183
Realized and unrealized losses recognized in earnings, net		(16,727		)
Realized and unrealized losses recognized in other comprehensive income, net		(4,122		)
Purchases		23,867
Issuances		(2,160		)
Settlements		(3,830		)
Balance, end of period		$	6,211

Net unrealized losses during the twelve months ended December 31, 2011 related to level 3 financial instruments held on December 31, 2011 were $13.1 million.

Fair Value of Long-Term Debt

At December 31, 2011 and December 31, 2010, the fair value of the Company's senior notes and other long-term debt, including amounts classified as current, was $4.2 billion and $1.7 billion, respectively. Fair values are based upon observed prices in an active market when available or from valuation models using market information.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 44A, 44B
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 15C, 15D
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 15A
-Subparagraph a-d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 15B
-Subparagraph a, b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 3, 10, 14, 15
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 157
-Paragraph 32, 33, 34
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 159
-Paragraph 17-22, 27, 28
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 21
-URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13537-108611

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14064-108612

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
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-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13433-108611

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 30
-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14172-108612

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 16
-URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13504-108611

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
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-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19296-110258

+ Details

Asset Retirement Obligations

12 Months Ended

Dec. 31, 2011

Asset Retirement Obligations [Abstract]

Asset Retirement Obligations

14. Asset Retirement Obligations

The Company's asset retirement obligations arise from the Federal Surface Mining Control and Reclamation Act of 1977 and similar state statutes, which require that mine property be restored in accordance with specified standards and an approved reclamation plan. The required reclamation activities to be performed are outlined in the Company's mining permits. These activities include reclaiming the pit and support acreage at surface mines, sealing portals at underground mines, and reclaiming refuse areas and slurry ponds.

The following table describes the changes to the Company's asset retirement obligation liability:


	Year Ended December 31
	2011	2010
	(In thousands)
Balance at January 1 (including current portion)	$ 343,119	$ 310,409
Accretion expense	33,601	26,615
Obligations incurred or acquired	115,019	—
Adjustments to the liability from changes in estimates	11,176	8,934
Liabilities settled	(29,012)	(2,839)
Balance at December 31	$ 473,903	$ 343,119
Current portion included in accrued expenses	(27,119)	(8,862)
Noncurrent liability	$ 446,784	$ 334,257

Liabilities settled of $29.0 million in 2011 related to reclamation activities at the Black Thunder mining complex related to a pit acquired with the Jacobs Ranch operations in 2009.

As of December 31, 2011, the Company had $263.0 million in surety bonds outstanding and $420.5 million in self-bonding to secure reclamation obligations.

Accrued Workers' Compensation

12 Months Ended

Dec. 31, 2011

Accrued Workers' Compensation [Abstract]

Accrued Workers' Compensation

15. Accrued Workers' Compensation

The Company is liable under the Federal Mine Safety and Health Act of 1969, as subsequently amended, to provide for pneumoconiosis (occupational disease) benefits to eligible employees, former employees, and dependents. The Company is also liable under various states' statutes for occupational disease benefits. The Company currently provides for federal and state claims principally through a self-insurance program. The occupational disease benefit obligation represents the present value of the actuarially computed present and future liabilities for such benefits over the employees' applicable years of service.

In addition, the Company is liable for workers' compensation benefits for traumatic injuries that are accrued as injuries are incurred. Traumatic claims are either covered through self-insured programs or through state-sponsored workers' compensation programs.

Workers' compensation expense consists of the following components:


	Year Ended December 31
	2011	2010	2009
	(In thousands)
Self-insured occupational disease benefits:
Service cost	$ 2,059	$ 727	$ 531
Interest cost	1,799	675	558
Net amortization	(493)	(1,860)	(2,879)
Total occupational disease	3,365	(458)	(1,790)
Traumatic injury claims and assessments	16,979	9,263	8,904
Total workers' compensation expense	$ 20,344	$ 8,805	$ 7,114

The increase in total workers' compensation expense for the year ended 2011 is related to the acquisition of ICG.

The reconciliation of changes in the benefit obligation of the occupational disease liability is as follows:


	December 31
	2011	2010
	(In thousands)
Beginning of year obligation	$ 17,412	$ 9,702
Service cost	2,059	727
Interest cost	1,799	675
Actuarial loss	7,081	6,993
Benefit and administrative payments	(1,097)	(685)
Acquisition of ICG	26,930	—
Net obligation at end of year	$ 54,184	$ 17,412

At December 31, 2011 and 2010, accumulated losses of $5.5 million and accumulated gains of $2.0 million, respectively, were not yet recognized in occupational disease cost and were recorded in accumulated other comprehensive income. The expected accumulated loss that will be amortized from accumulated other comprehensive income into occupational disease cost in 2012 is $1.1 million.

The following table provides the assumptions used to determine the projected occupational disease obligation:


	Year Ended December 31
	2011	2010	2009
Weighted average assumptions:
Discount rate	5.10%	5.96%	6.11%
Cost escalation rate	3.00%	3.00%	3.00%

Summarized below is information about the amounts recognized in the accompanying consolidated balance sheets for workers' compensation benefits:


	December 31
	2011	2010
	(In thousands)
Occupational disease costs	$ 54,184	$ 17,412
Traumatic and other workers' compensation claims	29,430	24,537
Total obligations	83,614	41,949
Less amount included in accrued expenses	11,666	6,659
Noncurrent obligations	$ 71,948	$ 35,290

As of December 31, 2011, the Company had $60.1 million in surety bonds and letters of credit outstanding to secure workers' compensation obligations.

Employee Benefit Plans

12 Months Ended

Dec. 31, 2011

Employee Benefit Plans [Abstract]

Employee Benefit Plans

16. Employee Benefit Plans

Defined Benefit Pension and Other Postretirement Benefit Plans

The Company provides funded and unfunded non-contributory defined benefit pension plans covering certain of its salaried and hourly employees. Benefits are generally based on the employee's age and compensation. The Company funds the plans in an amount not less than the minimum statutory funding requirements or more than the maximum amount that can be deducted for U.S. federal income tax purposes.

The Company also currently provides certain postretirement medical and life insurance coverage for eligible employees. Generally, covered employees who terminate employment after meeting eligibility requirements are eligible for postretirement coverage for themselves and their dependents. The salaried employee postretirement benefit plans are contributory, with retiree contributions adjusted annually, and contain other cost-sharing features such as deductibles and coinsurance. The Company's current funding policy is to fund the cost of all postretirement benefits as they are paid.

Employees acquired with the ICG acquisition were brought over in their existing plan. Subsequently, the terms of the plan were amended to change vesting periods, coverage caps, and eligible ages, resulting in a reduction of the benefit obligation of $55.5 million.

During 2009, the Company notified participants of the retiree medical plan of a plan change increasing the retirees' responsibility for medical costs. This change resulted in a remeasurement of the postretirement benefit obligation, which included a decrease in the discount rate from 6.85% to 5.68%. The remeasurement resulted in a decrease in the liability of $21.0 million, with a corresponding increase to other comprehensive income, and will result in future reductions in costs under the plan.

Obligations and Funded Status. Summaries of the changes in the benefit obligations, plan assets and funded status of the plans are as follows:


	Pension Benefits		Other Postretirement Benefits
	2011	2010	2011	2010
	(In thousands)
CHANGE IN BENEFIT OBLIGATIONS
Benefit obligations at January 1	$ 297,707	$ 280,693	$ 39,633	$ 46,445
Service cost	16,490	15,870	3,917	1,509
Interest cost	16,253	15,822	3,279	2,083
Plan amendments	(3,235)	(92)	(55,542)	—
Benefits paid	(18,848)	(15,924)	(1,669)	(1,845)
Acquisition of ICG	—	—	48,441	—
Other-primarily actuarial loss (gain)	25,584	1,338	7,070	(8,559)
Benefit obligations at December 31	$ 333,951	$ 297,707	$ 45,129	$ 39,633
CHANGE IN PLAN ASSETS
Value of plan assets at January 1	$ 247,713	$ 211,899	$ —	$ —
Actual return on plan assets	9,443	34,401	—	—
Employer contributions	46,766	17,337	1,669	1,845
Benefits paid	(18,848)	(15,924)	(1,669)	(1,845)
Value of plan assets at December 31	$ 285,074	$ 247,713	$ —	$ —
Accrued benefit cost	$ (48,877)	$ (49,994)	$ (45,129)	$ (39,633)
ITEMS NOT YET RECOGNIZED AS A COMPONENT OF NET PERIODIC BENEFIT COST
Prior service credit (cost)	$ 1,736	$ (1,310)	$ 62,920	$ 9,742
Accumulated gain (loss)	(68,302)	(39,099)	1,795	11,965
	$ (66,566)	$ (40,409)	$ 64,715	$ 21,707
BALANCE SHEET AMOUNTS
Current liability	$ (633)	$ (840)	$ (2,820)	$ (1,840)
Noncurrent liability	$ (48,244)	$ (49,154)	$ (42,309)	$ (37,793)
	$ (48,877)	$ (49,994)	$ (45,129)	$ (39,633)

Pension Benefits

The accumulated benefit obligation for all pension plans was $314.7 million and $280.4 million at December 31, 2011 and 2010, respectively. The accumulated benefit obligation differs from the benefit obligation in that it includes no assumption about future compensation levels.

The benefit obligation and the accumulated benefit obligation for the Company's unfunded pension plan were $8.2 million and $7.1 million, respectively, at December 31, 2011.

The prior service credit and net loss that will be amortized from accumulated other comprehensive income into net periodic benefit cost in 2012 are $0.1 million and $14.3 million, respectively.

Other Postretirement Benefits

The prior service credit and net gain that will be amortized from accumulated other comprehensive income into net periodic benefit cost in 2012 is $12.0 million and $0.4 million, respectively.

Components of Net Periodic Benefit Cost. The following table details the components of pension and other postretirement benefit costs.


	Pension Benefits			Other Postretirement Benefits
Year Ended December 31,	2011	2010	2009	2011	2010	2009
	(In thousands)
Service cost	$ 16,490	$ 15,870	$ 13,444	$ 3,917	$ 1,509	$ 2,954
Interest cost	16,253	15,822	15,946	3,279	2,083	3,667
Expected return on plan assets*	(21,812)	(19,392)	(17,719)	—	—	—
Amortization of prior service cost (credit)	(189)	173	193	(2,364)	(2,364)	2,161
Amortization of other actuarial losses (gains)	8,748	7,130	3,967	(3,100)	(2,918)	(2,897)
Curtailments	—	—	585	—	—	—
Net benefit cost	$ 19,490	$ 19,603	$ 16,416	$ 1,732	$ (1,690)	$ 5,885

____________

*	The Company does not fund its other postretirement benefit obligations.

The differences generated from changes in assumed discount rates and returns on plan assets are amortized into earnings over a five-year period.

Assumptions. The following table provides the assumptions used to determine the actuarial present value of projected benefit obligations at December 31.


	Pension Benefits		Other Postretirement Benefits
	2011	2010	2011	2010
Weighted average assumptions:
Discount rate	4.91%	5.71%	4.52%	5.23%
Rate of compensation increase	3.39%	3.39%	N/A	N/A

The following table provides the assumptions used to determine net periodic benefit cost for years ended December 31.


	Pension Benefits			Other Postretirement Benefits
	2011	2010	2009	2011	2010	2009
Weighted average assumptions:
Discount rate	5.71%	5.97%	6.85%	5.23%	5.67%	6.85%/5.68%
Rate of compensation increase	3.39%	3.39%	3.39%	N/A	N/A	N/A
Expected return on plan assets	8.50%	8.50%	8.50%	N/A	N/A	N/A

The Company establishes the expected long-term rate of return at the beginning of each fiscal year based upon historical returns and projected returns on the underlying mix of invested assets. The Company utilizes modern portfolio theory modeling techniques in the development of its return assumptions. This technique projects rates of return that can be generated through various asset allocations that lie within the risk tolerance set forth by members of the Company's pension committee (the "Pension Committee"). The risk assessment provides a link between a pension's risk capacity, management's willingness to accept investment risk and the asset allocation process, which ultimately leads to the return generated by the invested assets.

The health care cost trend rate assumed for 2012 is 7.7% and is expected to reach an ultimate trend rate of 4.5% by 2028. A one-percentage-point increase in the health care cost trend rate would have increased the postretirement benefit obligation at December 31, 2011 by $0.5 million. A one-percentage-point decrease in the health care cost trend rate would have decreased the postretirement benefit obligation at December 31, 2011 by $0.4 million. The effect of these changes would have had an insignificant impact on the net periodic postretirement benefit costs.

Plan Assets

The Pension Committee is responsible for overseeing the investment of pension plan assets. The Pension Committee is responsible for determining and monitoring appropriate asset allocations and for selecting or replacing investment managers, trustees and custodians. The pension plan's current investment targets are 65% equity, 30% fixed income securities and 5% cash. The Pension Committee reviews the actual asset allocation in light of these targets on a periodic basis and rebalances among investments as necessary. The Pension Committee evaluates the performance of investment managers as compared to the performance of specified benchmarks and peers and monitors the investment managers to ensure adherence to their stated investment style and to the plan's investment guidelines.

The Company's pension plan assets at December 31, 2011 and 2010, respectively, are categorized below according to the fair value hierarchy as defined in Note 13, "Fair Values of Financial Instruments":


	Total		Level 1				Level 2		Level 3
	2011	2010		2011	2010	2011		2010		2011	2010
	(In thousands)
Equity securities:(A)
U.S. small-cap	$11,178	$10,647		$11,178	$10,647	$ —		$ —		$ —	$ —
U.S. mid-cap	50,264	46,851		23,474	21,163	26,790		25,688		—	—
U.S. large-cap	91,561	77,632		44,820	38,397	46,741		39,235		—	—
Non-U.S.	22,509	24,995		—	—	22,509		24,995		—	—
Fixed income securities:
U.S. government securities(B)	13,454	3,053		12,738	2,492	716		561		—	—
Non-U.S. government securities(C)	2,968	3,469		—	—	2,968		3,469		—	—
U.S. government asset and mortgage backed securities(D)	800	1,073		—	—	800		1,073		—	—
Corporate fixed income(E)	14,004	13,737		—	—	14,004		13,737		—	—
State and local government securities(F)	18,416	13,679		—	—	18,416		13,679		—	—
Other fixed income(G)	51,470	45,628		—	—	51,470		45,628		—	—
Short-term investments(H)	8,029	6,110		—	—	8,029		6,110		—	—
Other investments(I)	421	839		—	—	421		839		—	—
Total	$285,074	$247,713		$92,210	$72,699	$192,864		$175,014		$ —	$ —

____________

(A)	Equity securities includes investments in 1) common stock, 2) preferred stock and 3) mutual funds. Investments in common and preferred stocks are valued using quoted market prices multiplied by the number of shares owned. Investments in mutual funds are valued at the net asset value per share multiplied by the number of shares held as of the measurement date and are traded on listed exchanges.

(B)	U.S. government securities includes agency and treasury debt. These investments are valued using dealer quotes in an active market.

(C)	Non-U.S. government securities includes debt securities issued by foreign governments and are valued utilizing a price spread basis valuation technique with observable sources from investment dealers and research vendors.

(D)	U.S. government asset and mortgage backed securities includes government-backed mortgage funds which are valued utilizing an income approach that includes various valuation techniques and sources such as discounted cash flows models, benchmark yields and securities, reported trades, issuer trades and/or other applicable data.

(E)	Corporate fixed income is primarily comprised of corporate bonds and certain corporate asset-backed securities that are denominated in the U.S. dollar and are investment-grade securities. These investments are valued using dealer quotes.

(F)	State and local government securities include different U.S. state and local municipal bonds and asset backed securities, these investments are valued utilizing a market approach that includes various valuation techniques and sources such as value generation models, broker quotes, benchmark yields and securities, reported trades, issuer trades and/or other applicable data.

(G)	Other fixed income investments are actively managed fixed income vehicles that are valued at the net asset value per share multiplied by the number of shares held as of the measurement date.

(H)	Short-term investments include governmental agency funds, government repurchase agreements, commingled funds, and pooled funds and mutual funds. Governmental agency funds are valued utilizing an option adjusted spread valuation technique and sources such as interest rate generation processes, benchmark yields and broker quotes. Investments in governmental repurchase agreements, commingled funds and pooled funds and mutual funds are valued at the net asset value per share multiplied by the number of shares held as of the measurement date.

(I)	Other investments includes cash, forward contracts, derivative instruments, credit default swaps, interest rate swaps and mutual funds. Investments in interest rate swaps are valued utilizing a market approach that includes various valuation techniques and sources such as value generation models, broker quotes in active and non-active markets, benchmark yields and securities, reported trades, issuer trades and/or other applicable data. Forward contracts and derivative instruments are valued at their exchange listed price or broker quote in an active market. The mutual funds are valued at the net asset value per share multiplied by the number of shares held as of the measurement date and are traded on listed exchanges.

Cash Flows. In order to achieve a desired funded status, the Company expects to make contributions of $24.5 million to the pension plans in 2012.

The following represents expected future benefit payments, which reflect expected future service, as appropriate:

	Pension Benefits	Other Postretirement Benefits
	(In thousands)
2012	$ 17,898	$ 3,411
2013	20,854	3,787
2014	22,803	4,060
2015	22,492	4,406
2016	26,185	4,694
Years 2017-2021	164,788	25,122
	$ 275,020	$ 45,480

Other Plans

The Company sponsors savings plans which were established to assist eligible employees provide for their future retirement needs. The Company's expense, representing its contributions to the plans, was $25.9 million, $18.1 million and $15.9 million for the years ended December 31, 2011, 2010 and 2009, respectively.

- Definition

The entire disclosure for pension and other postretirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph a
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
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-Subparagraph h
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-Name Statement of Financial Accounting Standard (FAS)
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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef
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-Number 132R
-Paragraph 8
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Reference 7: http://www.xbrl.org/2003/role/presentationRef
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-Name Statement of Financial Accounting Standard (FAS)
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-Paragraph 264
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-Paragraph 8
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-Name Accounting Principles Board Opinion (APB)
-Number 30
-Paragraph 26
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef
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Reference 11: http://www.xbrl.org/2003/role/presentationRef
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-Name Statement of Financial Accounting Standard (FAS)
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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 12: http://www.xbrl.org/2003/role/presentationRef
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-Name Statement of Financial Accounting Standard (FAS)
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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/topic&trid=2235017

+ Details

Capital Stock	12 Months Ended
Capital Stock	Dec. 31, 2011
Capital Stock [Abstract]
Capital Stock	17. Capital Stock On March 14, 2006, the Company filed a registration statement on Form S-3 with the SEC. The registration statement allows the Company to offer, from time to time, an unlimited amount of debt securities, preferred stock, depositary shares, purchase contracts, purchase units, common stock and related rights and warrants. *Common Stock* On June 8, 2011, the Company sold 48 million shares of its common stock at a public offering price of $27.00 per share. The $1.25 billion in net proceeds from the issuance were used to finance the acquisition of ICG. On July 8, 2011, the Company issued an additional 0.7 million shares of its common stock under the same terms and conditions to cover underwriters' over-allotments for net proceeds of $18.4 million. On July 31, 2009, the Company sold 17 million shares of its common stock at a public offering price of $17.50 per share and on August 6, 2009, the Company issued an additional 2.55 million shares of its common stock under the same terms and conditions to cover underwriters' over-allotments. The net proceeds received from the issuance of common stock were $326.5 million, which was used primarily to finance the purchase of the Jacobs Ranch mining complex in 2009. *Stock Repurchase Plan* The Company's share repurchase program allows for the purchase of up to 14,000,000 shares of the Company's common stock. At December 31, 2011, 10,925,800 shares of common stock were available for repurchase under the plan. There were no purchases made under the plan during 2011, 2010 or 2009. There is no expiration date on the program. Any future repurchases under the plan will be made at management's discretion and will depend on market conditions and other factors.

- Definition

The entire disclosure for shareholders' equity, comprised of portions attributable to the parent entity and noncontrolling interest, if any, including other comprehensive income (as applicable). Including, but not limited to: (1) balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings; (2) accumulated balance for each classification of other comprehensive income and total amount of comprehensive income; (3) amount and nature of changes in separate accounts, including the number of shares authorized and outstanding, number of shares issued upon exercise and conversion, and for other comprehensive income, the adjustments for reclassifications to net income; (4) rights and privileges of each class of stock authorized; (5) basis of treasury stock, if other than cost, and amounts paid and accounting treatment for treasury stock purchased significantly in excess of market; (6) dividends paid or payable per share and in the aggregate for each class of stock for each period presented; (7) dividend restrictions and accumulated preferred dividends in arrears (in aggregate and per share amount); (8) retained earnings appropriations or restrictions, such as dividend restrictions; (9) impact of change in accounting principle, initial adoption of new accounting principle and correction of an error in previously issued financial statements; (10) shares held in trust for Employee Stock Ownership Plan (ESOP); (11) deferred compensation related to issuance of capital stock; (12) note received for issuance of stock; (13) unamortized discount on shares; (14) description, terms, and number of warrants or rights outstanding; (15) shares under subscription and subscription receivables, effective date of new retained earnings after quasi-reorganization and deficit eliminated by quasi-reorganization and, for a period of at least ten years after the effective date, the point in time from which the new retained dates; and (16) retroactive effective of subsequent change in capital structure.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Principles Board Opinion (APB)
-Number 12
-Paragraph 10
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Name Regulation S-X (SX)
-Number 210
-Section 04
-Article 3

Reference 3: http://www.xbrl.org/2003/role/presentationRef
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-Name Regulation S-X (SX)
-Number 210
-Article 4
-Section 08
-Paragraph d

Reference 4: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Research Bulletin (ARB)
-Number 43
-Chapter 1
-Section B
-Paragraph 7, 11A
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef
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-Name Statement of Financial Accounting Standard (FAS)
-Number 129
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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
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-Number 210
-Section 08
-Article 4

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
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Reference 9: http://www.xbrl.org/2003/role/presentationRef
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-Section E

Reference 10: http://www.xbrl.org/2003/role/presentationRef
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+ Details

Stock Based Compensation And Other Incentive Plans

12 Months Ended

Dec. 31, 2011

Stock Based Compensation And Other Incentive Plans [Abstract]

Stock Based Compensation And Other Incentive Plans

18. Stock Based Compensation and Other Incentive Plans

Under the Company's Stock Incentive Plan (the "Incentive Plan"), 18,000,000 shares of the Company's common stock are reserved for awards to officers and other selected key management employees of the Company. The Incentive Plan provides the Board of Directors with the flexibility to grant stock options, stock appreciation rights, restricted stock awards, restricted stock units, performance stock or units, merit awards, phantom stock awards and rights to acquire stock through purchase under a stock purchase program ("Awards"). Awards the Board of Directors elects to pay out in cash do not count against the 18,000,000 shares authorized in the Incentive Plan. The Incentive Plan calls for the adjustment of shares awarded under the plan in the event of a split.

As of December 31, 2011, the Company had stock options, restricted stock and restricted stock units outstanding under the Incentive Plan.

Stock Options

Stock options are granted at a price equal to the closing market price of the Company's common stock on the date of grant and are generally subject to vesting provisions of at least one year from the date of grant. Information regarding stock option activity under the Incentive Plan follows for the year ended December 31, 2011:

	Common Shares	Weighted Average Exercise Price	Aggregate Intrinsic Value	Average Contract Life
	(In thousands)		(In thousands)
Options outstanding at January 1	4,544	$ 25.18
Granted	728	32.18
Exercised	(199)	11.61
Canceled	(88)	23.74
Expired	(32)	52.69
Options outstanding at December 31	4,953	26.60	$ 4,107	5.76
Options exercisable at December 31	3,157	27.59	3,887	4.35

The aggregate intrinsic value of options exercised during the years ended December 31, 2011, 2010 and 2009 was $2.6 million, $3.0 million and $0.1 million, respectively.

Information regarding changes in stock options outstanding and not yet vested and the related grant-date fair value under the Incentive Plan follows for the year ended December 31, 2011:

	Common Shares	Weighted Average Grant-Date Fair Value
	(In thousands)
Unvested options at January 1	1,901	$ 10.61
Granted	728	14.18
Vested	(746)	13.28
Canceled	(87)	10.35
Unvested options at December 31	1,796	10.96

Compensation expense related to stock options for the years ended December 31, 2011, 2010 and 2009 was $8.8 million, $10.6 million and $11.8 million, respectively. As of December 31, 2011, there was $8.2 million of unrecognized compensation cost related to the unvested stock options. The total grant-date fair value of options vested during the years ended December 31, 2011, 2010 and 2009 was $9.9 million, $10.6 million and $9.1 million, respectively. The options provide for the continuation of vesting for retirement-eligible recipients that meet certain criteria. The expense for these options is recognized through the date that the employee first becomes eligible to retire and is no longer required to provide service to earn part or all of the award. The majority of the cost relating to the stock-based compensation plans is included primarily in selling, general and administrative expenses in the accompanying consolidated statements of income.

Weighted average assumptions used in the Black-Scholes option pricing model for granted options follow:


	Year Ended December 31
	2011	2010	2009
Weighted average grant-date fair value per share of options granted	$ 14.18	$ 9.43	$ 6.63
Assumptions (weighted average):
Risk-free interest rate	1.92%	2.16%	1.75%
Expected dividend yield	1.25%	1.99%	2.56%
Expected volatility	57.4%	57.1%	69.3%
Expected life (in years)	4.5	4.5	4.5

Expected volatilities are based on historical stock price movement and implied volatility from traded options on the Company's stock. The expected life of the option was determined based on historical exercise activity. Most options granted vest over a period of four years.

Restricted Stock and Restricted Stock Unit Awards

The Company may issue restricted stock and restricted stock units, which require no payment from the employee. Restricted stock cliff-vests at various dates and restricted stock units typically vest ratably over three years. Compensation expense is based on the fair value on the grant date and is recorded ratably over the vesting period. During the vesting period, the employee receives cash compensation equal to the amount of dividends that would have been paid on the underlying shares.

Information regarding restricted stock and restricted stock unit activity and weighted average grant-date fair value follows for the year ended December 31, 2011:


	Restricted Stock		Restricted Stock Units
	Common Shares	Weighted Average Grant-Date Fair Value	Common Shares	Weighted Average Grant-Date Fair Value
	(In thousands)		(In thousands)
Outstanding at January 1	74	$ 24.69	54	$ 52.69
Granted	140	30.42	—	—
Vested	(27)	39.77	(27)	52.69
Canceled	(5)	32.49	—	—
Outstanding at December 31	182	26.68	27	52.69

The weighted average fair value of restricted stock granted during 2010 and 2009 was $22.03 and $14.05, respectively. There were no restricted stock units granted during 2010 or 2009. The total grant-date fair value of restricted stock that vested during 2011, 2010 and 2009 was $1.1 million, $0.4 million and $1.5 million, respectively. The total grant-date fair value of restricted stock units that vested during 2011 and 2009 was $1.4 million and $0.4 million, respectively. There were no restricted stock units that vested during 2010. Unearned compensation of $3.4 million will be recognized over the remaining vesting period of the outstanding restricted stock and restricted stock units. The Company recognized expense of approximately $2.1 million, $1.1 million and $1.7 million related to restricted stock and restricted stock units for the years ended December 31, 2011, 2010 and 2009, respectively, primarily in selling, general and administrative expenses.

Long-Term Incentive Compensation

The Company has a long-term incentive program that allows for the award of performance units. The total number of units earned by a participant is based on financial and operational performance measures, and may be paid out in cash or in shares of the Company's common stock. The Company recognizes compensation expense over the three year term of the grant. The liabilities are remeasured quarterly. The Company recognized $2.7 million, $3.8 million and $2.6 million for the years ended December 31, 2011, 2010 and 2009, respectively. The expense is included primarily in selling, general and administrative expenses in the accompanying consolidated statements of income. Amounts accrued under the plan were $9.6 million and $6.4 million at December 31, 2011 and 2010, respectively.

Deferred Compensation Plan

The Company maintains a deferred compensation plan that allows eligible employees to defer receipt of compensation until the dates elected by the participant. Participants in the plan may defer up to 85% of their base salaries and up to 100% of their annual incentive awards. The plan also allows participants to defer receipt of up to 100% of the shares under any restricted stock unit or performance-contingent stock awards. The amounts deferred are invested in accounts that mirror the gains and losses of a number of different investment funds, including a hypothetical investment in shares of the Company's common stock. Participants are always vested in their deferrals to the plan and any related earnings. The Company has established a grantor trust to fund the obligations under the plan. The trust has purchased corporate-owned life insurance to offset these obligations. The net cash surrender values of the policies of $35.8 million and $40.7 million at December 31, 2011 and 2010, respectively, are included in other noncurrent assets in the accompanying consolidated balance sheets. The participants have an unsecured contractual commitment by the Company to pay the amounts due under the plan. Any assets placed in trust by the Company to fund future obligations of the plan are subject to the claims of creditors in the event of insolvency or bankruptcy, and participants are general creditors of the company as to their deferred compensation in the plans.

Under the plan, the Company credits each participant's account with the number of units equal to the number of shares or units that the participant could purchase or receive with the amount of compensation deferred, based upon the fair market value of the underlying investment on that date. The amount the employee will receive from the plan will be based on the number of units credited to each participant's account, valued on the basis of the fair market value of an equivalent number of shares or units of the underlying investment on that date. The liability under the plan was $32.7 million at December 31, 2011 and $38.5 million at December 31, 2010.

The Company's net income (expense) related to the deferred compensation plan for the years ended December 31, 2011, 2010 and 2009 was $6.2 million, $(2.8) million and $4.1 million, respectively, most of which is included in selling, general and administrative expenses in the accompanying consolidated statements of income.

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 123R
-Paragraph 64, 65, A240
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Statement of Position (SOP)
-Number 93-6
-Paragraph 53
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 14

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 50
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6406099&loc=d3e25284-112666

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901

Reference 6: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5444-113901

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 40
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6418621&loc=d3e17540-113929

+ Details

Risk Concentrations

12 Months Ended

Dec. 31, 2011

Risk Concentrations [Abstract]

Risk Concentrations

19. Risk Concentrations

Credit Risk and Major Customers

The Company has a formal written credit policy that establishes procedures to determine creditworthiness and credit limits for trade customers and counterparties in the over-the-counter coal market. Generally, credit is extended based on an evaluation of the customer's financial condition. Collateral is not generally required, unless credit cannot be established. Credit losses are provided for in the financial statements and historically have been minimal.

The Company markets its steam coal principally to electric utilities in the United States and its metallurgical coal to domestic and foreign steel producers. Revenues from export sales were $920.0 million, $471.5 million and $194.4 million for the years ended December 31, 2011, 2010 and 2009, respectively. The increasing export sales are primarily the result of an increase in metallurgical-quality coal sales volumes, although steam coal exports also increased. As of December 31, 2011 and 2010, accounts receivable from electric utilities located in the United States totaled $261.2 million and $183.1 million, respectively, or 69% and 88% of total trade receivables, respectively. As of December 31, 2011 and 2010, accounts receivable from sales of metallurgical-quality coal totaled $117.4 million and $24.9 million, respectively, or 31% and 12%, of total trade receivables, respectively.

The Company uses shipping destination as the basis for attributing revenue to individual countries. The Company's foreign revenues by geographical location for the year ended December 31, 2011, follows:

	December 31, 2011
	(In thousands)
Europe	$ 427,514
South America	120,842
North America	97,255
Asia	61,308
Brokered sales	213,087
Total	$ 920,006

The Company is committed under long-term contracts to supply steam coal that meets certain quality requirements at specified prices. These prices are generally adjusted based on indices. Quantities sold under some of these contracts may vary from year to year within certain limits at the option of the customer. The Company sold approximately 156.9 million tons of coal in 2011. Approximately 72% of this tonnage (representing approximately 57% of the Company's revenue) was sold under long-term contracts (contracts having a term of greater than one year). Long-term contracts range in remaining life from one to nine years. Sales (including spot sales) to the Company's largest customer, Tennessee Valley Authority, were $266.8 million, $301.4 million and $278.8 million for the years ended December 31, 2011, 2010 and 2009, respectively.

Third-party sources of coal

The Company uses independent contractors to mine coal at certain mining complexes. The Company also purchases coal from third parties that it sells to customers. Factors beyond the Company's control could affect the availability of coal produced for or purchased by the Company. Disruptions in the quantities of coal produced for or purchased by the Company could impair its ability to fill customer orders or require it to purchase coal from other sources at prevailing market prices in order to satisfy those orders.

Transportation

The Company depends upon barge, rail, truck and belt transportation systems to deliver coal to its customers. Disruption of these transportation services due to weather-related problems, mechanical difficulties, strikes, lockouts, bottlenecks, and other events could temporarily impair the Company's ability to supply coal to its customers, resulting in decreased shipments. In the past, disruptions in rail service have resulted in missed shipments and production interruptions.

- Definition

The entire disclosure for any concentrations existing at the date of the financial statements that make an entity vulnerable to a reasonably possible, near-term, severe impact. This disclosure informs financial statement users about the general nature of the risk associated with the concentration, and may indicate the percentage of concentration risk as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 15A
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Statement of Position (SOP)
-Number 94-6
-Paragraph 21, 22, 24
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 21
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-Name Accounting Standards Codification
-Topic 275
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-Section 50
-Paragraph 16
-URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6327-108592

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-Name Accounting Standards Codification
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-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13531-108611

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6351-108592

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
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-Name Accounting Standards Codification
-Topic 275
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-URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6442-108592

+ Details

Earnings Per Common Share

12 Months Ended

Dec. 31, 2011

Earnings Per Common Share [Abstract]

Earnings Per Common Share

20. Earnings per Common Share

The following table provides the basis for earnings per share calculations by reconciling basic and diluted weighted average shares outstanding:


	Year Ended December 31
	2011	2010	2009
	(In thousands)
Weighted average shares outstanding:
Basic weighted average shares outstanding	190,086	162,398	150,963
Effect of common stock equivalents under incentive plans	819	812	309
Diluted weighted average shares outstanding	190,905	163,210	151,272

The effect of options to purchase 2.6 million, 2.5 million and 2.2 million shares of common stock were excluded from the calculation of diluted weighted average shares outstanding for the years ended December 31, 2011, 2010 and 2009, respectively, because the exercise price of these options exceeded the average market price of the Company's common stock for this period.

Leases

12 Months Ended

Dec. 31, 2011

Leases [Abstract]

Leases

21. Leases

The Company leases equipment, land and various other properties under non-cancelable long-term leases, expiring at various dates. Certain leases contain options that would allow the Company to extend the lease or purchase the leased asset at the end of the base lease term. In addition, the Company enters into various non-cancelable royalty lease agreements under which future minimum payments are due.

Minimum payments due in future years under these agreements in effect at December 31, 2011 are as follows:

	Operating Leases	Royalties
	(In thousands)
2012	$ 28,903	$ 24,378
2013	27,610	25,595
2014	25,119	25,810
2015	17,641	27,565
2016	9,648	24,397
Thereafter	12,640	114,371
	$ 121,561	$ 242,116

Rental expense, including amounts related to these operating leases and other shorter-term arrangements, amounted to $43.9 million in 2011, $41.6 million in 2010 and $43.3 million in 2009.

Royalties are paid to lessors either as a fixed price per ton or as a percentage of the gross sales price of the mined coal. Royalties under the majority of the Company's significant leases are paid on a percentage royalty basis. Royalty expense, including production royalties, was $349.0 million in 2011, $286.8 million in 2010 and $230.5 million in 2009.

As of December 31, 2011, certain of the Company's lease obligations were secured by outstanding surety bonds totaling $64.6 million.

- Definition

The entire disclosure for lessee entity's leasing arrangements including, but not limited to, all of the following: (a.) The basis on which contingent rental payments are determined, (b.) The existence and terms of renewal or purchase options and escalation clauses, (c.) Restrictions imposed by lease agreements, such as those concerning dividends, additional debt, and further leasing.

+ References + Details

Guarantees and Commitments	12 Months Ended
Guarantees and Commitments	Dec. 31, 2011
Guarantees [Abstract]
Guarantees and Commitments	22. Guarantees and Commitments The Company has agreed to continue to provide surety bonds and letters of credit for the reclamation and retiree healthcare obligations of Magnum Coal Company ("Magnum") related to the properties the Company sold to Magnum on December 31, 2005. Patriot Coal Corporation ("Patriot") acquired Magnum in July 2008. The purchase agreement requires Magnum to reimburse the Company for costs related to the surety bonds and letters of credit and to use commercially reasonable efforts to replace the obligations. If the surety bonds and letters of credit related to the reclamation obligations are not replaced by Magnum within a specified period of time, Magnum must post a letter of credit in favor of the Company in the amounts of the reclamation obligations. As of December 31, 2011, Patriot had replaced $48.9 million of the surety bonds and posted letters of credit of $16.1 million in the Company's favor. At December 31, 2011, the Company had $38.5 million of surety bonds remaining related to properties sold to Magnum. The surety bonding amounts are mandated by the state and are not directly related to the estimated cost to reclaim the properties. Magnum also acquired certain coal supply contracts with customers who did not consent to the assignment of the contract from the Company to Magnum. The Company has committed to purchase coal from Magnum to fulfill these contracts at the same price it is charging the customers for the sale. In addition, certain contracts were assigned to Magnum, but the Company has guaranteed Magnum's performance under the contracts. The longest of the coal supply contracts extends to the year 2017. If Magnum is unable to supply the coal for these coal sales contracts then the Company would be required to purchase coal on the open market or supply contracts from its existing operations. At market prices effective at December 31, 2011, the cost of purchasing 9.8 million tons of coal to supply over their duration the contracts that were not assigned would exceed the sales price under the contracts by approximately $199.4 million, and the cost of purchasing 0.7 million tons of coal to supply over their duration the assigned and guaranteed contracts would exceed the sales price under the contracts by approximately $15.3 million. As the Company does not believe that it is probable that it would have to purchase replacement coal, no losses have been recorded in the consolidated financial statements as of December 31, 2011. However, if the Company would have to perform under these guarantees, it could potentially have a material adverse effect on the business, results of operations and financial condition of the Company. In connection with the Company's acquisition of the coal operations of ARCO and the simultaneous combination of the acquired ARCO operations and the Company's Wyoming operations into the Arch Western joint venture, the Company agreed to indemnify the other member of Arch Western against certain tax liabilities in the event that such liabilities arise prior to June 1, 2013 as a result of certain actions taken, including the sale or other disposition of certain properties of Arch Western, the repurchase of certain equity interests in Arch Western by Arch Western or the reduction under certain circumstances of indebtedness incurred by Arch Western in connection with the acquisition. If the Company were to become liable, the maximum amount of potential future tax payments was $19.3 million at December 31, 2011, which is not recorded as a liability in the Company's consolidated financial statements. Since the indemnification is dependent upon the initiation of activities within the Company's control and the Company does not intend to initiate such activities, it is remote that the Company will become liable for any obligation related to this indemnification. However, if such indemnification obligation were to arise, it could potentially have a material adverse effect on the business, results of operations and financial condition of the Company. The Company has unconditional purchase obligations relating to purchases of coal, materials and supplies and capital commitments, other than reserve acquisitions, and is also a party to transportation capacity commitments. The future commitments under these agreements total $487.5 million in 2012, $139.2 million in 2013, $175.0 million in 2014, $163.9 million in 2015, $128.3 million in 2016 and $154.8 million thereafter. These commitments include the cost of coal purchases from Magnum as discussed above. During the years ended December 31, 2011, 2010 and 2009, the Company fulfilled its commitments under agreements containing unconditional obligations.

Contingencies	12 Months Ended
Contingencies	Dec. 31, 2011
Contingencies [Abstract]
Contingencies	23. Contingencies The following matters relate to certain claims and legal actions involving ICG and/or its subsidiaries. Allegheny Energy Supply ("Allegheny"), the sole customer of coal produced at the Company's subsidiary Wolf Run Mining Company's ("Wolf Run") Sycamore No. 2 mine, filed a lawsuit against Wolf Run, Hunter Ridge Holdings, Inc. ("Hunter Ridge"), and ICG in state court in Allegheny County, Pennsylvania on December 28, 2006, and amended its complaint on April 23, 2007. Allegheny claimed that Wolf Run breached a coal supply contract when it declared force majeure under the contract upon idling the Sycamore No. 2 mine in the third quarter of 2006, and that Wolf Run continued to breach the contract by failing to ship in volumes referenced in the contract. The Sycamore No. 2 mine was idled after encountering adverse geologic conditions and abandoned gas wells that were previously unidentified and unmapped. After extensive searching for gas wells and rehabilitation of the mine, it was re-opened in 2007, but with notice to Allegheny that it would necessarily operate at reduced volumes in order to safely and effectively avoid the many gas wells within the reserve. The amended complaint also alleged that the production stoppages constitute a breach of the guarantee agreement by Hunter Ridge and breach of certain representations made upon entering into the contract in early 2005. Allegheny voluntarily dropped the breach of representation claims later. Allegheny claimed that it would incur costs in excess of $100 million to purchase replacement coal over the life of the contract. ICG, Wolf Run and Hunter Ridge answered the amended complaint on August 13, 2007, disputing all of the remaining claims. On November 3, 2008, ICG, Wolf Run and Hunter Ridge filed an amended answer and counterclaim against the plaintiffs seeking to void the coal supply agreement due to, among other things, fraudulent inducement and conspiracy. On September 23, 2009, Allegheny filed a second amended complaint alleging several alternative theories of liability in its effort to extend contractual liability to ICG, which was not a party to the original contract and did not exist at the time Wolf Run and Allegheny entered into the contract. No new substantive claims were asserted. ICG answered the second amended complaint on October 13, 2009, denying all of the new claims. ICG's counterclaim was dismissed on motion for summary judgment entered on May 11, 2010. Allegheny's claims against ICG were also dismissed by summary judgment, but the claims against Wolf Run and Hunter Ridge were not. The court conducted a non-jury trial of this matter beginning on January 10, 2011 and concluding on February 1, 2011. At the trial, Allegheny presented its evidence for breach of contract and claimed that it is entitled to past and future damages in the aggregate of between $228.0 million and $377.0 million. Wolf Run and Hunter Ridge presented their defense of the claims, including evidence with respect to the existence of force majeure conditions and excuse under the contract and applicable law. Wolf Run and Hunter Ridge presented evidence that Allegheny's damages calculations were significantly inflated because it did not seek to determine damages as of the time of the breach and in some instances artificially assumed future non-delivery or did not take into account the apparent requirement to supply coal in the future. On May 2, 2011, the trial court entered a Memorandum and Verdict determining that Wolf Run had breached the coal supply contract and that the performance shortfall was not excused by force majeure. ICG and Allegheny filed post-verdict motions in the trial court and on August 23, 2011, the court denied the parties' motions. The court entered a final judgment on August 25, 2011, in the amount of $104.1 million, which included pre-judgment interest. The parties appealed the lower court's decision to the Superior Court of Pennsylvania. Wolf Run and Hunter Ridge have filed an appeal bond in the amount of $124.9 million. Briefing is scheduled to begin on October 24, 2011, to be completed in early 2012. As of December 31, 2011, the Company has accrued $108.3 million for this lawsuit, including $3.4 million of interest recognized post-acquisition. The ultimate resolution of this matter could result in an outcome which may be materially different than what the Company has accrued. In addition, the Company is a party to numerous claims and lawsuits with respect to various matters. The Company provides for costs related to contingencies when a loss is probable and the amount is reasonably determinable. After conferring with counsel, it is the opinion of management that the ultimate resolution of pending claims, other than as noted above, will not have a material adverse effect on the consolidated financial condition, results of operations or liquidity of the Company.

- Definition

The entire disclosure for loss and gain contingencies. Describes any existing condition, situation, or set of circumstances involving uncertainty as of the balance sheet date (or prior to issuance of the financial statements) as to a probable or reasonably possible loss incurred by an entity that will ultimately be resolved when one or more future events occur or fail to occur, and typically discloses the amount of loss recorded or a range of possible loss, or an assertion that no reasonable estimate can be made.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Interpretation (FIN)
-Number 14
-Paragraph 3
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 5
-Paragraph 9, 10, 11, 12
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14326-108349

Reference 4: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-Name Accounting Standards Codification
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-Name Accounting Standards Codification
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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14615-108349

+ Details

Segment Information

12 Months Ended

Dec. 31, 2011

Segment Information [Abstract]

Segment Information

24. Segment Information

The Company has three reportable business segments, which are based on the major coal producing basins in which the Company operates. Each of these reportable business segments includes a number of mine complexes. The Company manages its coal sales by coal basin, not by individual mine complex. Geology, coal transportation routes to customers, regulatory environments and coal quality are characteristic to a basin. Accordingly, market and contract pricing have developed by coal basin. Mine operations are evaluated based on their per-ton operating costs (defined as including all mining costs but excluding pass-through transportation expenses), as well as on other non-financial measures, such as safety and environmental performance. The Company's reportable segments are the Powder River Basin (PRB) segment, with operations in Wyoming; the Western Bituminous (WBIT) segment, with operations in Utah, Colorado and southern Wyoming; the Appalachia (APP) segment, with operations in West Virginia, Kentucky, Maryland and Virginia. The Appalachia segment includes the acquired ICG operations in Appalachia, as well as the Company's previous Central Appalachia segment. The "Other" operating segment represents primarily the Company's Illinois operations and ADDCAR subsidiary, which manufactures and sells its patented highwall mining system.

Operating segment results for the years ended December 31, 2011, 2010 and 2009 are presented below. Results for the reportable segments include all direct costs of mining, including all depreciation, depletion and amortization related to the mining operations, even if the assets are not recorded at the operating segment level. See discussion of segment assets below. Corporate, Other and Eliminations includes the change in fair value of coal derivatives and coal trading activities, net; corporate overhead; land management; other support functions; and the elimination of intercompany transactions.

The asset amounts below represent an allocation of assets used in the segments' cash-generating activities. The amounts in Corporate, Other and Eliminations represent primarily corporate assets (cash, receivables, investments, plant, property and equipment) as well as unassigned coal reserves, above-market acquired sales contracts and other unassigned assets.


	PRB	APP	WBIT		Other Operating Segments		Corporate, Other and Eliminations		Consolidated
	(In thousands)
December 31, 2011
Revenues	$ 1,646,947	$ 1,915,090		$ 672,766		$ 51,092		$ —		$ 4,285,895
Income (loss) from operations	180,730	283,404		119,665		(4,685)		(165,538)		413,576
Total assets	2,307,783	4,740,723		681,393		581,040		1,903,020		10,213,959
Depreciation, depletion and amortization	171,693	203,759		81,235		7,876		2,024		466,587
Amortization of acquired sales contracts, net	19,458	(39,988)		—		(1,539)		—		(22,069)
Capital expenditures	110,999	217,435		66,356		28,243		117,903		540,936
December 31, 2010
Revenues	$ 1,606,236	$ 1,042,490		$ 537,542		$ —		$ —		$ 3,186,268
Income from operations	146,555	193,943		58,082		—		(74,596)		323,984
Total assets	2,295,786	706,624		677,611		—		1,200,748		4,880,769
Depreciation, depletion and amortization	185,218	97,764		80,497		—		1,587		365,066
Amortization of acquired sales contracts, net	35,606	—		—		—		—		35,606
Capital expenditures	38,142	70,839		65,470		—		140,206		314,657
December 31, 2009
Revenues	$ 1,205,492	$ 829,895		$ 540,694		$ —		$ —		$ 2,576,081
Income from operations	82,341	105,241		29,722		—		(93,590)		123,714
Total assets	2,421,917	734,309		687,873		—		996,497		4,840,596
Depreciation, depletion and amortization	127,378	88,409		83,781		—		2,040		301,608
Amortization of acquired sales contracts, net	19,934	—		(311)		—		—		19,623
Capital expenditures	58,275	48,673		67,299		—		148,903		323,150

A reconciliation of segment income from operations to consolidated income before income taxes follows:


	Year Ended December 31
	2011	2010	2009
	(In thousands)
Income from operations	$ 413,576	$ 323,984	$ 123,714
Interest expense	(230,186)	(142,549)	(105,932)
Interest income	3,309	2,449	7,622
Bridge financing costs related to ICG	(49,490)	—	—
Loss on early extinguishment of debt	(1,958)	(6,776)	—
Income before income taxes	$ 135,251	$ 177,108	$ 25,404

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 131
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8981-108599

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 35
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8984-108599

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e9054-108599

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e9031-108599

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 31
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8924-108599

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8538-108599

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
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-Paragraph 30
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8906-108599

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e9038-108599

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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Reference 12: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 280
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Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8380-108599

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
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-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8595-108599

Reference 15: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
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-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8933-108599

+ Details

Quarterly Financial Information

12 Months Ended

Dec. 31, 2011

Quarterly Financial Information [Abstract]

Quarterly Financial Information

25. Quarterly Financial Information (Unaudited)

Quarterly financial data for the years ended December 31, 2011 and 2010 is summarized below:

	March 31	June 30	September 30	December 31
		(a)(b)	(a)(b)	(a)
	(In thousands, except per share data)
2011:
Revenues	$ 872,938	$ 985,528	$ 1,198,673	$ 1,228,756
Gross profit	129,773	171,440	118,974	153,280
Income from operations	102,238	95,354	76,256	139,728
Net income	55,874	6,630	9,121	71,215
Basic earnings per common share	0.34	0.04	0.04	0.34
Diluted earnings per common share	0.34	0.04	0.04	0.33

	March 31	June 30	September 30	December 31
		(c)	(d)
	(In thousands, except per share data)
2010:
Revenues	$ 711,874	$ 764,295	$ 874,705	$ 835,394
Gross profit	61,852	100,461	119,957	107,514
Income from operations	32,200	106,499	98,347	86,938
Net income (loss)	(1,770)	66,274	46,859	48,031
Basic earnings (loss) per common share	(0.01)	0.41	0.29	0.29
Diluted earnings (loss) per common share	(0.01)	0.41	0.29	0.29

____________

(a)	The Company expensed costs related to the acquisition of ICG $98.2 million, $4.7 million and $1.3 million in the second, third and fourth quarters of 2011, respectively.

(b)	The amounts above differ from those previously reported because of fair value adjustments related to the ICG acquisition made in the fourth quarter of 2011 and pushed back to the respective reporting periods. Net income in the second quarter of 2011 decreased $4.8 million, using an effective tax rate of 37%, from what was originally reported due to increases in cost of sales and depreciation, depletion and amortization expense and net income in the third quarter of 2011 decreased $10.2 million, using an effective tax rate of 37%, from what was originally reported due to an increase in depreciation, depletion and amortization expense.

(c)	In the second quarter of 2010, the Company exchanged 68.4 million tons of coal reserves in the Illinois Basin for an additional 9% ownership interest in Knight Hawk. The Company recognized a gain of $41.6 million on the transaction.

(d)	The Company's Dugout Canyon mine in Carbon County, Utah suspended operations on April 29, 2010 after an increase in carbon monoxide levels resulted from a heating event in a previously mined area. After permanently sealing the area, full coal production resumed on May 21, 2010. On June 22, 2010, an ignition event at the longwall resulted in a second evacuation of all underground employees at the mine. All employees were safely evacuated in both events. The resumption of mining required rendering the mine's atmosphere inert, ventilating the longwall area, determining the cause of the ignition, implementing preventive measures, and securing an MSHA-approved longwall ventilation plan. The longwall system resumed production at normalized levels by the end of September.

- Definition

The entire disclosure for the quarterly financial data in the annual financial statements. The disclosure may include a tabular presentation of financial information for each fiscal quarter for the current and previous year, including revenues, gross profit, income or loss before extraordinary items and earnings per share data. It also includes an indication if the information in the note is unaudited, comments on the aggregate effect of year-end adjustments, and an explanation of matters or transactions that affect comparability or are pertinent to an understanding of the information furnished.

+ References + Details

Supplemental Condensed Consolidating Financial Information

12 Months Ended

Dec. 31, 2011

Supplemental Condensed Consolidating Financial Information [Abstract]

Supplemental Condensed Consolidating Financial Information

26. Supplemental Condensed Consolidating Financial Information

Pursuant to the indentures governing Arch Coal, Inc.'s senior notes, certain wholly-owned subsidiaries of the Company have fully and unconditionally guaranteed the senior notes on a joint and several basis. The following tables present condensed consolidating financial information for (i) the Company, (ii) the issuer of the senior notes, (iii) the guarantors under the senior notes, and (iv) the entities which are not guarantors under the senior notes (Arch Western Resources, LLC and its subsidiaries, Arch Receivable Company, LLC and the Company's subsidiaries outside the U.S.):

CONDENSED CONSOLIDATING STATEMENTS OF INCOME

Year Ended December 31, 2011

Parent/Issuer

Guarantor

Subsidiaries

Non-Guarantor Subsidiaries

Eliminations

Consolidated

(In thousands)


Revenues	$ –	$2,024,168	$ 2,261,727	$ –	$ 4,285,895

Costs, expenses and other
Cost of sales	22,925	1,537,697	1,812,461	(105,173)	3,267,910
Depreciation, depletion and amortization	2,883	304,742	158,962	–	466,587
Amortization of acquired sales contracts, net	–	(41,527)	19,458	–	(22,069)
Selling, general and administrative expenses	74,591	13,860	37,839	(7,234)	119,056
Change in fair value of coal derivatives and coal trading activities, net	–	(2,907)	–	–	(2,907)
Acquisition and transition costs	54,676	–	–	–	54,676
Other operating (income) expense, net	(23,306)	(118,767)	18,732	112,407	(10,934)

	131,769	1,693,098	2,047,452	-	3,872,319

Income from investment in subsidiaries	556,448	–	–	(556,448)	–

Income from operations	424,679	331,070	214,275	(556,448)	413,576
Interest income (expense), net:
Interest expense	(256,220)	(5,062)	(43,728)	74,824	(230,186)
Interest income	16,282	759	61,092	(74,824)	3,309
	(239,938)	(4,303)	17,364	–	(226,877)

Other non-operating expense
Bridge financing costs related to ICG	(49,490)	-	-	-	(49,490)
Net loss resulting from early retirement of debt	–	(1,958)	-	–	(1,958)
	(49,490)	(1,958)	-	–	(51,448)

Income before income taxes	135,251	324,809	231,639	(556,448)	135,251
Benefit from income taxes	(7,589)	–	–	–	(7,589)

Net income	142,840	324,809	231,639	(556,448)	142,840
Less: Net income attributable to noncontrolling interest	(1,157)	–	–	–	(1,157)

Net income attributable to Arch Coal	$ 141,683	$ 324,809	$ 231,639	$(556,448)	$141,683

CONDENSED CONSOLIDATING STATEMENTS OF INCOME

Year Ended December 31, 2010

	Parent/Issuer	Guarantor Subsidiaries	Non-Guarantor Subsidiaries	Eliminations	Consolidated
	(In thousands)

Revenues	$ —	$ 1,137,980	$ 2,048,288	$ —	$ 3,186,268

Costs, expenses and other
Cost of sales	11,526	797,917	1,679,872	(93,503)	2,395,812
Depreciation, depletion and amortization	2,933	194,847	167,286	—	365,066
Amortization of acquired sales contracts, net	—	—	35,606	—	35,606
Selling, general and administrative expenses	79,580	7,355	38,496	(7,254)	118,177
Change in fair value of coal derivatives and coal trading activities, net	—	8,924	—	—	8,924
Gain on Knight Hawk transaction	—	(41,577)	—	—	(41,577)
Other operating (income) expense, net	(10,259)	(115,994)	5,772	100,757	(19,724)
	83,780	851,472	1,927,032	—	2,862,284
Income from investment in subsidiaries	393,366	—	—	(393,366)	—

Income from operations	309,586	286,508	121,256	(393,366)	323,984

Interest expense, net:
Interest expense	(143,606)	(2,763)	(64,463)	68,283	(142,549)
Interest income	11,128	456	59,148	(68,283)	2,449
	(132,478)	(2,307)	(5,315)	—	(140,100)
Other non-operating expense
Net loss resulting from early retirement of debt	—	—	(6,776)	—	(6,776)
	—	—	(6,776)	—	(6,776)

Income before income taxes	177,108	284,201	109,165	(393,366)	177,108
Provision for income taxes	17,714	—	—	—	17,714
Net income	159,394	284,201	109,165	(393,366)	159,394
Less: Net income attributable to noncontrolling interest	(537)	—	—	—	(537)
Net income attributable to Arch Coal	$ 158,857	$ 284,201	$ 109,165	$ (393,366)	$ 158,857

CONDENSED CONSOLIDATING STATEMENTS OF INCOME

Year Ended December 31, 2009

	Parent/Issuer	Guarantor Subsidiaries	Non-Guarantor Subsidiaries	Eliminations	Consolidated
	(In thousands)

Revenues	$ —	$ 924,692	$ 1,651,389	$ —	$ 2,576,081

Costs, expenses and other
Cost of sales	7,481	713,782	1,398,663	(49,211)	2,070,715
Depreciation, depletion and amortization	3,678	138,125	159,805	—	301,608
Amortization of acquired sales contracts, net	—	—	19,623	—	19,623
Selling, general and administrative expenses	49,672	7,504	46,563	(5,952)	97,787
Change in fair value of coal derivatives and coal trading activities, net	—	(12,056)	—	—	(12,056)
Acquisition and transition costs	13,726	—	—	—	13,726
Other operating (income) expense, net	(12,909)	(85,460)	4,170	55,163	(39,036)
	61,648	761,895	1,628,824	—	2,452,367
Income from investment in subsidiaries	165,183	—	—	(165,183)	—

Income from operations	103,535	162,797	22,565	(165,183)	123,714

Interest expense, net:
Interest expense	(92,371)	(2,442)	(70,668)	59,549	(105,932)
Interest income	14,240	720	52,211	(59,549)	7,622
	(78,131)	(1,722)	(18,457)	—	(98,310)

Income before income taxes	25,404	161,075	4,108	(165,183)	25,404
Benefit from income taxes	(16,775)	—	—	—	(16,775)
Net income	42,179	161,075	4,108	(165,183)	42,179
Less: Net income attributable to noncontrolling interest	(10)	—	—	—	(10)
Net income attributable to Arch Coal	$ 42,169	$ 161,075	$ 4,108	$ (165,183)	$ 42,169

CONDENSED CONSOLIDATING BALANCE SHEETS

December 31, 2011

	Parent/Issuer	Guarantor Subsidiaries	Non-Guarantor Subsidiaries	Eliminations	Consolidated
	(In thousands)
ASSETS
Cash and cash equivalents	$ 61,375	$ 332	$ 76,442	$ –	$ 138,149
Restricted cash	10,322	–	–	–	10,322
Receivables	65,187	22,037	383,572	(1,617)	469,179
Inventories	–	207,050	170,440	–	377,490
Other	81,732	83,122	22,780	–	187,634
Total current assets	218,616	312,541	653,234	(1,617)	1,182,774
Property, plant and equipment, net	21,241	6,403,658	1,524,251	–	7,949,150
Investment in subsidiaries	8,805,731	–	–	(8,805,731)	–
Intercompany receivables	(1,457,864)	7,010	1,450,854	–	–
Note receivable from Arch Western	225,000	–	–	(225,000)	–
Other	184,266	884,613	13,156	–	1,082,035
Total other assets	7,757,133	891,623	1,464,010	(9,030,731)	1,082,035
Total assets	$ 7,996,990	$7,607,822	$ 3,641,495	(9,032,348)	$10,213,959
LIABILITIES AND STOCKHOLDERS' EQUITY
Accounts payable	$ 25,409	$ 175,196	$ 183,177	$ –	$ 383,782
Accrued expenses and other current liabilities	75,133	115,685	166,834	(1,617)	356,035
Current maturities of debt and short-term borrowings	172,564	1,987	106,300	–	280,851
Total current liabilities	273,106	292,868	456,311	(1,617)	1,020,668
Long-term debt	3,308,674	2,652	450,971		3,762,297
Note payable to Arch Coal	–	–	225,000	(225,000)	–
Asset retirement obligations	877	140,861	305,046	–	446,784
Accrued pension benefits	19,198	4,203	24,843	–	48,244
Accrued postretirement benefits other than pension	13,843	6,271	22,195	–	42,309
Accrued workers' compensation	17,272	48,111	6,565	–	71,948
Deferred income taxes	621,483	355,270	–	–	976,753
Other noncurrent liabilities	152,963	64,795	37,624	–	255,382
Total liabilities	4,407,416	915,031	1,528,555	(226,617)	6,624,385
Redeemable noncontrolling interest	11,534	–	–	–	11,534
Stockholders' equity	3,578,040	6,692,791	2,112,940	(8,805,731)	3,578,040
Total liabilities and stockholders' equity	$ 7,996,990	$7,607,822	$ 3,641,495	$ (9,032,348)	$10,213,959

CONDENSED CONSOLIDATING BALANCE SHEETS

December 31, 2010

	Parent/Issuer	Guarantor Subsidiaries	Non-Guarantor Subsidiaries	Eliminations	Consolidated
	(In thousands)
ASSETS
Cash and cash equivalents	$ 13,713	$ 64	$ 79,816	$ —	$ 93,593
Receivables	31,458	12,740	210,075	(1,953)	252,320
Inventories	—	85,196	150,420	—	235,616
Other	29,575	102,375	21,435	—	153,385
Total current assets	74,746	200,375	461,746	(1,953)	734,914
Property, plant and equipment, net	9,817	1,800,578	1,498,497	—	3,308,892
Investment in subsidiaries	4,555,233	—	—	(4,555,233)	—
Intercompany receivables	(1,807,902)	508,624	1,299,278	—	—
Note receivable from Arch Western	225,000	—	—	(225,000)	—
Other	481,345	344,698	10,920	—	836,963
Total other assets	3,453,676	853,322	1,310,198	(4,780,233)	836,963
Total assets	$ 3,538,239	$ 2,854,275	$ 3,270,441	$ (4,782,186)	$ 4,880,769
LIABILITIES AND STOCKHOLDERS' EQUITY
Accounts payable	$ 10,753	$ 65,793	$ 121,670	$ —	$ 198,216
Accrued expenses and other current liabilities	75,746	31,123	153,217	(1,953)	258,133
Current maturities of debt and short-term borrowings	14,093	—	56,904	—	70,997
Total current liabilities	100,592	96,916	331,791	(1,953)	527,346
Long-term debt	1,087,126	—	451,618	—	1,538,744
Note payable to Arch Coal	—	—	225,000	(225,000)	—
Asset retirement obligations	873	32,029	301,355	—	334,257
Accrued pension benefits	20,843	4,407	23,904	—	49,154
Accrued postretirement benefits other than pension	14,284	—	23,509	—	37,793
Accrued workers' compensation	15,383	13,805	6,102	—	35,290
Other noncurrent liabilities	51,187	22,135	36,912	—	110,234
Total liabilities	1,290,288	169,292	1,400,191	(226,953)	2,632,818
Redeemable noncontrolling interest	10,444	—	—	—	10,444
Stockholders' equity	2,237,507	2,684,983	1,870,250	(4,555,233)	2,237,507
Total liabilities and stockholders' equity	$ 3,538,239	$ 2,854,275	$ 3,270,441	$ (4,782,186)	$ 4,880,769

CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS

Year Ended December 31, 2011

	Parent/Issuer	Guarantor Subsidiaries	Non-Guarantor Subsidiaries	Eliminations	Consolidated
		(In thousands)
Cash provided by (used in) operating activities	$ (561,704)	$801,201	$ 402,745	$ –	$ 642,242
Investing Activities
Acquisitions of businesses, net of cash acquired	(2,894,339)	–	–	–	(2,894,339)
Decrease in restricted cash	5,167	–	–	–	5,167
Capital expenditures	(12,809)	(353,441)	(174,686)	–	(540,936)
Proceeds from dispositions of property, plant and equipment	–	25,730	157	–	25,887
Additions to prepaid royalties	-	(25,982)	(3,975)	-	(29,957)
Purchases of investments and advances to affiliates	(633,534)	(33,553)	-	605,178	(61,909)
Consideration paid related to prior business acquisitions	(829)	–	–	–	(829)
Cash used in investing activities	(3,536,344)	(387,246)	(178,504)	605,178	(3,496,916)
Financing Activities
Proceeds from the issuance of senior notes	2,000,000	–	–	–	2,000,000
Proceeds from the issuance of common stock, net	1,267,933	–	–	–	1,267,933
Contributions from parent	–	605,178	–	(605,178)	–
Payments to retire debt	–	(605,178)	–	–	(605,178)
Net increase (decrease) in borrowings under lines of credit and commercial paper program	481,300	–	(56,904)	–	424,396
Net proceeds from other debt	5,334	–	–	–	5,334
Debt financing costs	(114,799)	–	(24)	–	(114,823)
Dividends paid	(80,748)	–	–	–	(80,748)
Issuance of common stock under incentive plans	2,316	–	–	–	2,316
Transactions with affiliates, net	584,374	(413,687)	(170,687)	–	–
Cash provided by (used in) financing activities	4,145,710	(413,687)	(227,615)	(605,178)	2,899,230
Increase (decrease) in cash and cash equivalents	47,662	268	(3,374)	–	44,556
Cash and cash equivalents, beginning of period	13,713	64	79,816	–	93,593
Cash and cash equivalents, end of period	$ 61,375	$ 332	$ 76,442	$ –	$ 138,149

CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS

Year Ended December 31, 2010

	Parent/Issuer	Guarantor Subsidiaries	Non-Guarantor Subsidiaries	Consolidated
	(In thousands)
Cash provided by (used in) operating activities	$ (238,736)	$ 503,766	$ 432,117	$ 697,147
Investing Activities
Capital expenditures	(4,814)	(198,243)	(111,600)	(314,657)
Proceeds from dispositions of property, plant and equipment	—	251	79	330
Additions to prepaid royalties	—	(24,381)	(2,974)	(27,355)
Purchases of investments and advances to affiliates	(40,421)	(5,764)	—	(46,185)
Consideration paid related to prior business acquisitions	(1,262)	—	—	(1,262)
Cash used in investing activities	(46,497)	(228,137)	(114,495)	(389,129)
Financing Activities
Proceeds from the issuance of senior notes	500,000	—	—	500,000
Payments to retire debt	—	—	(505,627)	(505,627)
Net decrease in borrowings under lines of credit and commercial paper program	(120,000)	—	(76,549)	(196,549)
Net proceeds from other debt	82	—	—	82
Debt financing costs	(12,022)	—	(729)	(12,751)
Dividends paid	(63,373)	—	—	(63,373)
Issuance of common stock under incentive plans	1,764			1,764
Contribution from noncontrolling interest	—	—	891	891
Transactions with affiliates, net	(61,760)	(275,629)	337,389	—
Cash provided by (used in) financing activities	244,691	(275,629)	(244,625)	(275,563)
Increase (decrease) in cash and cash equivalents	(40,542)	—	72,997	32,455
Cash and cash equivalents, beginning of period	54,255	64	6,819	61,138
Cash and cash equivalents, end of period	$ 13,713	$ 64	$ 79,816	$ 93,593

CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS

Year Ended December 31, 2009

	Parent/Issuer	Guarantor Subsidiaries	Non-Guarantor Subsidiaries	Consolidated
	(In thousands)
Cash provided by (used in) operating activities	$ (168,427)	$ 338,956	$ 212,451	$ 382,980
Investing Activities
Acquisitions of businesses, net of cash acquired	(768,819)	—	—	(768,819)
Capital expenditures	(2,940)	(194,756)	(125,454)	(323,150)
Proceeds from dispositions of property, plant and equipment	—	734	91	825
Additions to prepaid royalties	—	(23,991)	(2,764)	(26,755)
Purchases of investments and advances to affiliates	(8,000)	(2,925)	—	(10,925)
Consideration paid related to prior business acquisitions	(4,767)	—	—	(4,767)
Reimbursement of deposits on equipment	—	—	3,209	3,209
Cash used in investing activities	(784,526)	(220,938)	(124,918)	(1,130,382)
Financing Activities
Proceeds from the issuance of senior notes	584,784	—	—	584,784
Proceeds from the sale of common stock, net	326,452	—	—	326,452
Net decrease in borrowings under lines of credit and commercial paper program	(85,000)	—	(815)	(85,815)
Net payments on other debt	(2,986)	—	—	(2,986)
Debt financing costs	(29,456)	—	(203)	(29,659)
Dividends paid	(54,969)	—	—	(54,969)
Issuance of common stock under incentive plans	84	—	—	84
Transactions with affiliates, net	200,562	(118,015)	(82,547)	—
Cash provided by (used in) financing activities	939,471	(118,015)	(83,565)	737,891
Increase (decrease) in cash and cash equivalents	(13,482)	3	3,968	(9,511)
Cash and cash equivalents, beginning of period	67,737	61	2,851	70,649
Cash and cash equivalents, end of period	$ 54,255	$ 64	$ 6,819	$ 61,138

Valuation And Qualifying Accounts

12 Months Ended

Dec. 31, 2011

Valuation And Qualifying Accounts [Abstract]

Valuation And Qualifying Accounts

Arch Coal, Inc. and Subsidiaries

Valuation and Qualifying Accounts

	Balance at Beginning of Year	Additions (Reductions) Charged to Costs and Expenses	Charged to Other Accounts	Deductions(a)	Balance at End of Year
	(In thousands)
Year ended December 31, 2011
Reserves deducted from asset accounts:
Other assets — other notes and accounts receivable	$ —	$ 17	$ —	$ —	$ 17
Current assets — supplies and inventory	12,701	1,755	—	1,349	13,107
Deferred income taxes	737	2,416	—	322	2,831
Year ended December 31, 2010
Reserves deducted from asset accounts:
Other assets — other notes and accounts receivable	$ 109	$ —	$ —	$ 109	$ —
Current assets — supplies and inventory	13,406	1,962	—	2,667	12,701
Deferred income taxes	1,120	(383)	—	—	737
Year ended December 31, 2009
Reserves deducted from asset accounts:
Other assets — other notes and accounts receivable	$ 225	$ (17)	$ —	$ 99	$ 109
Current assets — supplies and inventory	12,760	1,302	—	656	13,406
Deferred income taxes	395	725	—	—	1,120

____________

(a)	Reserves utilized, unless otherwise indicated.

Accounting Policies (Policy)	12 Months Ended
Accounting Policies (Policy)	Dec. 31, 2011
Accounting Policies [Abstract]
Basis Of Presentation	*Basis of Presentation* The consolidated financial statements include the accounts of Arch Coal, Inc. and its subsidiaries and controlled entities ("the Company"). The Company produces coal from surface and underground mines located throughout the United States for sale to domestic and international customers as steam coal to power plants and industrial facilities and metallurgical coal used in steel production. The Company expanded further into metallurgical coal markets with the acquisition of International Coal Group, Inc. ("ICG") on June 15, 2011, as described in Note 3, "Business Combinations." The Company operates 23 mining complexes in West Virginia, Kentucky, Maryland, Virginia, Illinois, Wyoming, Colorado and Utah. All subsidiaries (except as noted below) are wholly-owned. Intercompany transactions and accounts have been eliminated in consolidation. The Company owns a 99% membership interest in a joint venture named Arch Western Resources, LLC ("Arch Western"), which operates coal mines in Wyoming, Colorado and Utah. The Company also acts as the managing member of Arch Western.
Accounting Pronouncements Adopted And New Pronouncements Not Yet Implemented	*Accounting Pronouncements* There were no accounting pronouncements whose adoption had, or is expected to have, a material impact on the Company's consolidated financial statements.
Accounting Estimates	*Accounting Estimates* The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and revenues and expenses in the accompanying consolidated financial statements and the disclosure of contingent assets and liabilities. Actual results could differ from those estimates.
Cash And Cash Equivalents	*Cash and Cash Equivalents* Cash and cash equivalents are stated at cost. Cash equivalents consist of highly-liquid investments with an original maturity of three months or less when purchased. At December 31, 2011 and 2010, the carrying amounts of cash and cash equivalents approximate their fair value.
Allowance For Uncollectible Receivables	*Allowance for Uncollectible Receivables* The Company establishes an allowance for uncollectible receivables for the amounts of trade accounts receivable and other receivables that are not expected to be collected, based on past collection history, the economic environment and specified risks identified in the receivables portfolio. Receivables are considered past due if the full payment is not received by the contractual due date. At December 31, 2011 and 2010, there was either no allowance or an insignificant allowance for uncollectible receivables.
Inventories	*Inventories* Coal and supplies inventories are valued at the lower of average cost or market. Coal inventory costs include labor, supplies, equipment costs, transportation costs incurred prior to the transfer of title to customers and operating overhead. The costs of removing overburden, called stripping costs, incurred during the production phase of the mine are considered variable production costs and are included in the cost of the coal extracted during the period the stripping costs are incurred.
Investments And Membership Interests In Joint Ventures	*Investments and Membership Interests in Joint Ventures* Investments and membership interests in joint ventures are accounted for under the equity method of accounting if the Company has the ability to exercise significant influence, but not control, over the entity. The Company's share of the entity's income is reflected in other operating income, net in the consolidated statements of income. Information about investment activity is provided in Note 8, "Equity Investments and Membership Interests in Joint Ventures." Marketable equity securities held by the Company that do not qualify for equity method accounting are classified as available-for-sale and are recorded at their fair value on the balance sheet. Unrealized gains and losses on these investments are recorded in other comprehensive income. A decline in the value of an investment that is considered other-than-temporary is recognized in income.
Prepaid Royalties	*Prepaid Royalties* Leased mineral rights are often acquired through royalty payments. When royalty payments represent prepayments recoupable against future production, they are recorded as a prepaid asset, with amounts expected to be recouped within one year classified as current. When the coal is mined under these leases the royalties are recouped and the prepayment is charged to cost of sales.
Acquired Sales Contracts	*Acquired Sales Contracts* Coal supply agreements (sales contracts) acquired in a business combination are capitalized at their fair value and amortized over the tons of coal shipped during the term of the contract. The fair value of a sales contract is determined by discounting the cash flows attributable to the difference between the contract price and the prevailing forward prices for the tons under contract at the date of acquisition. See Note 6, "Acquired Sales Contracts" for further information related to the Company's acquired sales contracts.
Exploration Costs	*Exploration Costs* Costs to acquire permits for exploration activities are capitalized. Drilling and other costs related to locating coal deposits and evaluating the economic viability of such deposits are expensed as incurred.
Property, Plant And Equipment	*Property, Plant and Equipment* Plant and Equipment Plant and equipment are recorded at cost. Interest costs incurred during the construction period for major asset additions are capitalized. Expenditures that extend the useful lives of existing plant and equipment or increase the productivity of the asset are capitalized. The cost of maintenance and repairs that do not extend the useful life or increase the productivity of the asset are expensed as incurred. Preparation plants and loadouts are depreciated using the units-of-production method over the estimated recoverable reserves, subject to a minimum level of depreciation. Other plant and equipment are depreciated principally using the straight-line method over the estimated useful lives of the assets, limited by the remaining life of the mine. The useful lives of mining equipment, including longwalls, draglines and shovels, range from 5 to 32 years. The useful lives of buildings and leasehold improvements generally range from 10 to 30 years. Deferred Mine Development Costs of developing new mines or significantly expanding the capacity of existing mines are capitalized and amortized using the units-of-production method over the estimated recoverable reserves that are associated with the property being benefited. Costs may include construction permits and licenses; mine design; construction of access roads, shafts, slopes and main entries; and removing overburden to access reserves in a new pit. Additionally, deferred mine development includes the asset cost associated with asset retirement obligations. Coal Lands and Mineral Rights Rights to coal reserves may be acquired directly through governmental or private entities. A significant portion of the Company's coal reserves are controlled through leasing arrangements. The net book value of the Company's leased coal interests was $1.6 billion at December 31, 2011 and 2010. Payments to acquire royalty lease agreements and lease bonus payments are capitalized as a cost of the underlying mineral reserves and depleted over the life of proven and probable reserves. Coal lease rights are depleted using the units-of-production method, and the rights are assumed to have no residual value. Lease agreements are generally long-term in nature (original terms range from 10 to 50 years), and substantially all of the leases contain provisions that allow for automatic extension of the lease term providing certain requirements are met. See Note 2, "Property Transactions" for further disclosures on coal lease agreements. Impairment If facts and circumstances suggest that the carrying value of a long-lived asset or asset group may not be recoverable, the asset or asset group is reviewed for potential impairment. If this review indicates that the carrying amount of the asset will not be recoverable through projected undiscounted cash flows generated by the asset and its related asset group over its remaining life, then an impairment loss is recognized by reducing the carrying value of the asset to its fair value. The Company may, under certain circumstances, idle mining operations in response to market conditions or other factors. Because an idling is not a permanent closure, it is not considered an automatic indicator of impairment.
Goodwill	*Goodwill* In a business combination, goodwill represents the excess of the purchase price over the fair value assigned to the net tangible and identifiable intangible assets acquired. The Company tests goodwill for impairment annually as of the beginning of the fourth quarter, or when circumstances indicate a possible impairment may exist. If the results of the testing indicate that the carrying amount of a reporting unit exceeds the fair value of the reporting unit, the fair value of goodwill must be calculated. An impairment loss generally would be recognized when the carrying amount of goodwill exceeds the implied fair value of goodwill, determined by subtracting the fair value of the other assets and liabilities associated with the reporting unit from the total fair value of the reporting unit. The fair value of a reporting unit is determined using a discounted cash flow ("DCF") technique. A number of significant assumptions and estimates are involved in the application of the DCF analysis to forecast operating cash flows, including the discount rate and projections of selling prices and costs to produce.
Deferred Financing Costs	*Deferred Financing Costs* The Company capitalizes costs incurred in connection with new borrowings, the establishment or enhancement of credit facilities and the issuance of debt securities. These costs are amortized as an adjustment to interest expense over the life of the borrowing or term of the credit facility using the interest method. The unamortized balance of deferred financing costs was $90.5 million and $37.6 million at December 31, 2011 and 2010, respectively. Amounts classified as current were $15.8 million and $9.6 million at December 31, 2011 and 2010, respectively. Current amounts are recorded in other current assets and noncurrent amounts are recorded in other assets in the accompanying consolidated balance sheets.
Revenue Recognition	*Revenue Recognition* Revenues include sales to customers of coal produced at Company operations and coal purchased from third parties. The Company recognizes revenue at the time risk of loss passes to the customer at contracted amounts. Transportation costs are included in cost of sales and amounts billed by the Company to its customers for transportation are included in revenues.
Other Operating Income, Net	*Other Operating Income, Net* Other operating income, net in the accompanying consolidated statements of income reflects income and expense from sources other than physical coal sales, including: bookouts, the practice of offsetting purchase and sale contracts for shipping convenience purposes, and contract settlements; royalties earned from properties leased to third parties; income from equity investments; gains and losses from dispositions of assets; and realized gains and losses on derivatives that do not qualify for hedge accounting and are not held for trading purposes.
Asset Retirement Obligations	*Asset Retirement Obligations* The Company's legal obligations associated with the retirement of long-lived assets are recognized at fair value at the time the obligations are incurred. Accretion expense is recognized through the expected settlement date of the obligation. Obligations are incurred at the time development of a mine commences for underground and surface mines or construction begins for support facilities, refuse areas and slurry ponds. The obligation's fair value is determined using a DCF technique and is based upon permit requirements and various estimates and assumptions that would be used by market participants, including estimates of disturbed acreage, reclamation costs and assumptions regarding equipment productivity. Upon initial recognition of a liability, a corresponding amount is capitalized as part of the carrying value of the related long-lived asset. The Company reviews its asset retirement obligation at least annually and makes necessary adjustments for permit changes as granted by state authorities and for revisions of estimates of the amount and timing of costs. For ongoing operations, adjustments to the liability result in an adjustment to the corresponding asset. For idle operations, adjustments to the liability are recognized as income or expense in the period the adjustment is recorded. Any difference between the recorded obligation and the actual cost of reclamation is recorded in profit or loss in the period the obligation is settled. See additional discussion in Note 14, "Asset Retirement Obligations."
Derivative Instruments	*Derivative Instruments* The Company generally utilizes derivative instruments to manage exposures to commodity prices. Additionally, the Company may hold certain coal derivative instruments for trading purposes. Derivative financial instruments are recognized in the balance sheet at fair value. Certain coal contracts may meet the definition of a derivative instrument, but because they provide for the physical purchase or sale of coal in quantities expected to be used or sold by the Company over a reasonable period in the normal course of business, they are not recognized on the balance sheet. Certain derivative instruments are designated as the hedge instrument in a hedging relationship. In a fair value hedge, the Company hedges the risk of changes in the fair value of a firm commitment, typically a fixed-price coal sales contract. Changes in both the hedged firm commitment and the fair value of a derivative used as a hedge instrument in a fair value hedge are recorded in earnings. In a cash flow hedge, the Company hedges the risk of changes in future cash flows related to a forecasted purchase or sale. Changes in the fair value of the derivative instrument used as a hedge instrument in a cash flow hedge are recorded in other comprehensive income. Amounts in other comprehensive income are reclassified to earnings when the hedged transaction affects earnings and are classified in a manner consistent with the transaction being hedged. The Company formally documents the relationships between hedging instruments and the respective hedged items, as well as its risk management objectives for hedge transactions. The Company evaluates the effectiveness of its hedging relationships both at the hedge's inception and on an ongoing basis. Any ineffective portion of the change in fair value of a derivative instrument used as a hedge instrument in a fair value or cash flow hedge is recognized immediately in earnings. The ineffective portion is based on the extent to which exact offset is not achieved between the change in fair value of the hedge instrument and the cumulative change in expected future cash flows on the hedged transaction from inception of the hedge in a cash flow hedge or the change in the fair value. Ineffectiveness was insignificant for the years ended December 31, 2011, 2010 and 2009. See Note 10, "Derivative Instruments" for further disclosures related to the Company's derivative instruments.
Fair Value	*Fair Value* Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly hypothetical transaction between market participants at a given measurement date. Valuation techniques used must maximize the use of observable inputs and minimize the use of unobservable inputs. See Note 13, "Fair Values of Financial Instruments" for further disclosures related to the Company's fair value estimates.
Income Taxes	*Income Taxes* Deferred income taxes are provided for temporary differences arising from differences between the financial statement amount and tax basis of assets and liabilities existing at each balance sheet date using enacted tax rates anticipated to be in effect when the related taxes are expected to be paid or recovered. A valuation allowance is established if it is more likely than not that a deferred tax asset will not be realized. In determining the need for a valuation allowance, the Company considers projected realization of tax benefits based on expected levels of future taxable income, available tax planning strategies and its overall deferred tax position. See Note 12, "Taxes" for further disclosures about income taxes.
Benefit Plans	*Benefit Plans* The Company has non-contributory defined benefit pension plans covering most of its salaried and hourly employees. Benefits are generally based on the employee's age and compensation. The Company also currently provides certain postretirement medical and life insurance coverage for eligible employees. The cost of providing these benefits are determined on an actuarial basis and accrued over the employee's period of active service. The Company recognizes the overfunded or underfunded status of these plans as determined on an actuarial basis on the balance sheet and the changes in the funded status are recognized in other comprehensive income. See Note 16, "Employee Benefit Plans" for additional disclosures relating to these obligations.
Stock-Based Compensation	*Stock-Based Compensation* The compensation cost of all stock-based awards is determined based on the grant-date fair value of the award, and is recognized in income over the requisite service period. The grant-date fair value of option awards is determined using a Black-Scholes option pricing model. Compensation cost for an award with performance conditions is accrued if it is probable that the conditions will be met. See further discussion in Note 18, "Stock Based Compensation and Other Incentive Plans."

Business Combination (Tables)

12 Months Ended

Dec. 31, 2011

Business Combinations [Abstract]

Summary Of Purchase Price Allocation


	(In millions)
Consideration paid, net of cash acquired	$	2,894.4
Recognized amounts of net tangible and intangible assets acquired and liabilities assumed:
Restricted cash	15.5
Receivables	113.2
Inventories	91.0
Net property, plant and equipment, including mineral rights	4,582.6
Goodwill	480.3
Other assets	35.9
Accounts payable	(86.0		)
Other accrued expenses and current liabilities	(59.1		)
Debt	(604.8		)
Litigation accrual	(108.9		)
Accrued postretirement benefits	(47.7		)
Asset retirement obligation	(112.7		)
Coal supply agreements, net	(91.0		)
Deferred income taxes, net	(1,278.9		)
Other	(35.0		)
Net tangible and intangible assets acquired	$	2,894.4

Summary Of Unaudited Pro Forma


		Year Ended December 31,
		2011				2010
			(In millions)
Total revenues
As reported	$	4,285.9		$	3,186.3
Pro forma	$	4,825.6		$	4,299.9

Net income attributable to Arch Coal
As reported	$	141.7		$	158.9
Pro forma	$	113.5		$	(1.2)

Schedule Of Costs And Expenses Reflected In The Income Before Income Taxes



		(In millions)
Costs of completing the acquisition	$	31.6
Severance costs		15.8
Write off of acquired assets		7.3
Bridge financing fees		49.5
	$	104.2

- Definition

Tabular disclosure of pro forma results of operations for a material business acquisition or series of individually immaterial business acquisitions that are material in the aggregate.

+ References + Details

Goodwill (Tables)

12 Months Ended

Dec. 31, 2011

Goodwill [Abstract]

Schedule Of Goodwill

		(In thousands)
Balance at January 1, 2009	$	46,832
Consideration paid related to prior business acquisitions		4,767
Acquisition of Jacobs Ranch		62,102
Balance at December 31, 2009		113,701
Consideration paid related to prior business acquisitions		1,262
Balance at December 31, 2010		114,963
Consideration paid related to prior business acquisitions		829
Acquisition of ICG		480,311
Balance at December 31, 2011	$	596,103

- Definition

Tabular disclosure of goodwill by reportable segment and in total. Disclosure details may include, but are not limited to, the carrying amount of goodwill, goodwill acquired during the year, goodwill impairment losses recognized, goodwill written-off due to the sale of a business unit, goodwill not yet allocated, and any other changes to goodwill.

+ References + Details

Debt And Financing Arrangements (Tables)

12 Months Ended

Dec. 31, 2011

Debt And Financing Arrangements [Abstract]

Debt And Financing Arrangements


		December 31,
		2011			2010
		(In thousands)
Commercial paper	$		—	$		56,904
Indebtedness to banks under credit facilities			481,300			—
6.75% senior notes ($450.0 million face value) due July 1, 2013			450,971			451,618
8.75% senior notes ($600.0 million face value) due August 1, 2016			588,974			587,126
7.00% senior notes due June 15, 2019 at par			1,000,000			—
7.25% senior notes due October 1, 2020 at par			500,000			500,000
7.25% senior notes due June 15, 2021 at par			1,000,000			—
Other			21,903			14,093
			4,043,148			1,609,741
Less current maturities of debt and short-term borrowings			280,851			70,997
Long-term debt	$		3,762,297	$		1,538,744

Acquired Sales Contracts (Tables)

12 Months Ended

Dec. 31, 2011

Acquired Sales Contracts [Abstract]

Schedule Of Acquired Sales Contracts


		December 31, 2011				December 31, 2010
		Assets		Liabilities		Assets		Liabilities
		(In thousands)				(In thousands)
Acquired fair value	$	149,457	$	166,697	$	114,453	$	40,654
Accumulated amortization		(115,322)		(69,699)		(82,376)		(14,613)
Total	$	34,135	$	96,998	$	32,077	$	26,041
Net total			$	(62,863)	$	6,036
Balance Sheet classification:
Other current	$	18,929	$	38,441	$	25,063	$	5,615
Other noncurrent	$	15,206	$	58,557	$	7,014	$	20,426

Accumulated Other Comprehensive Income (Loss) (Tables)

12 Months Ended

Dec. 31, 2011

Accumulated Other Comprehensive Income (Loss) [Abstract]

Components Of Accumulated Other Comprehensive Income (Loss)

	Derivative Instruments	Pension, Postretirement and Other Post- Employment Benefits	Available-for- Sale Securities	Accumulated Other Comprehensive Loss
	(In thousands)
Balance at January 1, 2009	$ (45,249)	$ (33,433)	$ (414)	$ (79,096)
2009 activity, before tax	72,553	20,124	(136)	92,541
2009 activity, tax effect	(26,118)	(7,230)	50	(33,298)
Balance at December 31, 2009	1,186	(20,539)	(500)	(19,853)
2010 activity, before tax	2,711	15,406	2,877	20,994
2010 activity, tax effect	(976)	(5,546)	(1,036)	(7,558)
Balance at December 31, 2010	2,921	(10,679)	1,341	(6,417)
2011 activity, before tax	(11,951)	9,345	176	(2,430)
2011 activity, tax effect	4,301	(3,342)	(62)	897
Balance at December 31, 2011	$ (4,729)	$ (4,676)	$ 1,455	$ (7,950)

Equity Investments And Membership Interests In Joint Ventures (Tables)

12 Months Ended

Dec. 31, 2011

Equity Investments And Membership Interests In Joint Ventures [Abstract]

Schedule Of Equity Method Investments

	Knight Hawk	DKRW	DTA	Tenaska	Millennium	Tongue River	Total
	(In thousands)

Balance at January 1 , 2009	$ 48,093	$ 25,124	$ 14,544	$ —	$ —	$ —	$ 87,761
Advances to (distributions from) affiliates, net	(5,164)	—	2,925	—	—	—	(2,239)
Equity in comprehensive income (loss)	6,674	(1,535)	(3,393)	—	—	—	1,746
Balance at December 31, 2009	49,603	23,589	14,076	—	—	—	87,268
Investments in affiliates	77,637	—	—	9,768	—	—	87,405
Advances to (distributions from) affiliates, net	(12,639)	—	4,264	—	—	—	(8,375)
Equity in comprehensive income (loss)	16,649	(1,628)	(3,868)	—	—	—	11,153
Balance at December 31, 2010	$ 131,250	$ 21,961	$ 14,472	$ 9,768	$ —	$ —	$ 177,451
Investments in affiliates	—	—	—	5,500	25,000	12,989	43,489
Advances to (distributions from) affiliates, net	(16,621)	—	6,498	—	3,477	—	(6,646)
Equity in comprehensive income (loss)	20,596	(2,246)	(4,884)	(2)	(2,153)	—	11,311
Balance at December 31, 2011	$ 135,225	$ 19,715	$ 16,086	$ 15,266	$ 26,324	$ 12,989	$ 225,605
Notes receivable from investees:
Balance at December 31, 2010	$ 1,700	$ 18,100	$ —	$ 4,100	$ —	$ —	$ 23,900
Balance at December 31, 2011	—	30,751	—	5,059	—	—	35,810

Summarized Financial Information Of Equity Method Investments


	December 31
	2011	2010	2009
Condensed combined income statement information:	(In thousands)
Revenues	$ 184,358	$ 172,933	$ 166,152
Gross profit	19,495	25,203	15,426
Income from operations	13,180	20,243	1,611
Net income (loss)	6,788	16,015	(1,797)

Condensed combined balance sheet information:
Current assets	$ 94,644	$ 48,202
Noncurrent assets	331,848	276,125
Total assets	$ 426,492	$ 324,327
Current liabilities	$ 51,674	$ 39,237
Noncurrent liabilities	120,494	99,350
Equity	254,163	185,639
Noncontrolling interest	161	101
Total liabilities and equity	$ 426,492	$ 324,327

Inventories (Tables)

12 Months Ended

Dec. 31, 2011

Inventories [Abstract]

Inventories


	December 31
	2011	2010
	(In thousands)
Coal	$ 206,517	$ 115,647
Repair parts and supplies	163,527	119,969
Work-in-process	7,446	—
	$ 377,490	$ 235,616

Derivative Instruments (Tables)

12 Months Ended

Dec. 31, 2011

Derivative Instruments [Abstract]

Derivative For Risk Management Purposes



	2012	2013	2014	2015
(Tons in thousands)
Coal sales	2,416	1,117	1,440	720
Coal purchases	254	—	—	—

Disclosure Of Fair Value Of Derivatives

Fair Value of Derivatives

(In thousands)


	December 31, 2011								December 31, 2010
	Asset Derivative			Liability Derivative					Asset Derivative			Liability Derivative
Derivatives Designated as Hedging Instruments
Heating oil – diesel purchases	$	8,997		$	—				$	13,475		$	—
Coal	1,109			—					2,009			(2,350		)
Total	10,106			—					15,484			(2,350		)
Derivatives Not Designated as Hedging Instruments
Heating oil – fuel surcharges	1,797			—					—			—
Coal — held for trading purposes	15,505			(19,927		)			34,445			(24,087		)
Coal	14,855			(6,035		)			1,139			(912		)
Total	32,157			(25,962		)			35,584			(24,999		)
Total derivatives	42,263			(25,962		)			51,068			(27,349		)
Effect of counterparty netting	(18,134		)	18,134					(22,402		)	22,402
Net derivatives as classified in the balance sheets	$	24,129		$	(7,828	)	$	16,301	$	28,666		$	(4,947	)	$	23,719

Net derivatives as reflected on the balance sheets


		December 31, 2011			December 31, 2010
Heating oil	Other current assets	$	10,794		$	13,475
Coal	Coal derivative assets	13,335			15,191
	Coal derivative liabilities	(7,828		)	(4,947		)
		$	16,301		$	23,719

Effects Of Derivatives On Measures Of Financial Performance

Derivatives used in

Fair Value Hedging

Gain on Derivatives Used in

Hedged Items in

Fair Value Hedge

Loss on Hedged Items In Fair Value

Relationships

Fair Value Hedge Relationships

Relationships

Hedge Relationships

2011

2010

2009

2011

2010

2009

(In thousands)

Coal

$ —

(3)

$ —

(3)

$ 2,586

(3)

Firm commitments

$ —

(3)

$ —

(3)

$ (2,586)

(3)


Derivatives used in Cash Flow Hedging	Gain (Loss) Recognized in OCI (Effective Portion)										Gains (Losses) Reclassified from OCI into Income (Effective Portion)
Relationships	2011			2010			2009			2011				2010			2009
Heating oil – diesel purchases	$	1,294		$	(149	)	$	10,309		$		14,866	(2)	$	437	(2)	$	(49,055	)	(2)
Coal sales	4,923			(4,714		)	(7,441		)	1,572			(1)	(1,602)		(1)	(6,999		)	(1)
Coal purchases	(2,009		)	5,145			1,089			—			(2)	(1,202)		(2)	(13,181		)	(2)
Totals	$	4,208		$	282		$	3,957		$		16,438		$	(2,367	)	$	(69,235)


Derivatives used in Cash Flow Hedging	Gain (Loss) Recognized in Income (Ineffective Portion and Amount Excluded from Effectiveness Testing)
Relationships	2011		2010		2009
Heating oil – diesel purchases	$	—	$	—	$ —
Coal sales	—		—		—
Coal purchases	—		—		—
Totals	$	—	$	—	$	—


Derivatives Not Designated as	Gain (Loss)
Hedging Instruments	2011			2010			2009
Coal — unrealized	$	6,438	(3)	$	(10,991)	(3)	$ 9,673	(3)
Coal — realized	$	(7)	(4)	$	4,542	(4)	$ —	(4)
Heating oil — fuel surcharges — unrealized	$	(2,906)	(4)	$	—	(4)	$ —	(4)

Location in Statement of Income:

(1) Revenues

(2) Cost of sales

(3) Change in fair value of coal derivatives and coal trading activities, net

(4) Other operating income, net

- Definition

Tabular disclosure of the location and amount of gains and losses reported in the statement of financial performance, or when applicable, the statement of financial position. For example, (a) gains and losses recognized in the income statement on derivative instruments designated and qualifying as hedging instruments in fair value hedges and related hedged items designated and qualifying in fair value hedges and (b) gains and losses initially recognized in other comprehensive income on derivative instruments designated and qualifying as cash flow hedges.

+ References + Details

Accrued Expenses And Other Current Liabilities (Tables)

12 Months Ended

Dec. 31, 2011

Accrued Expenses And Other Current Liabilities [Abstract]

Accrued Expenses and Other Current Liabilities


		December 31
	2011		2010
		(In thousands)
Payroll and employee benefits	$	65,323	$	51,327
Taxes other than income taxes		133,331		107,969
Interest		55,266		52,843
Acquired sales contracts (see Note 6)		38,441		5,615
Workers' compensation (see Note 15)		11,666		6,659
Asset retirement obligations (see Note 14)		27,119		8,862
Other		17,061		12,136
	$	348,207	$	245,411

Taxes (Tables)

12 Months Ended

Dec. 31, 2011

Taxes [Abstract]

Schedule Of Components Of Income Tax


	Year Ended December 31
	2011	2010	2009
	(In thousands)
Current:
Federal	$ (20,164)	$ 34,304	$ 21,295
State	1,212	2,283	864
Total current	(18,952)	36,587	22,159
Deferred:
Federal	13,214	(18,506)	(39,492)
State	(1,851)	(367)	558
Total deferred	11,363	(18,873)	(38,934)
	$ (7,589)	$ 17,714	$ (16,775)

Schedule Of Effective Income Tax Rate Reconciliation


	Year Ended December 31
	2011	2010	2009
	(In thousands)
Income tax expense at statutory rate	$ 46,933	$ 61,800	$ 8,888
Percentage depletion allowance	(61,971)	(49,152)	(29,463)
State taxes, net of effect of federal taxes	(3,055)	2,299	(61)
Change in valuation allowance	2,416	(383)	725
Other, net	8,088	3,150	3,136
	$ (7,589)	$ 17,714	$ (16,775)

Schedule Of Deferred Tax Assets And Liabilities


	December 31
	2011	2010
	(In thousands)
Deferred tax assets:
Alternative minimum tax credit carryforwards	$ 151,404	$ 170,592
Net operating loss carryforwards	324,393	102,355
Reclamation and mine closure	93,914	71,533
Advance royalties	—	38,557
Plant and equipment	—	19,846
Acquired sales contracts	44,717	20,120
Other, primarily accrued liabilities	171,715	90,412
Gross deferred tax assets	786,143	513,415
Valuation allowance	(2,831)	(737)
Total deferred tax assets	783,312	512,678
Deferred tax liabilities
Plant and equipment	1,566,769	—
Deferred development	67,728	76,690
Investment in tax partnerships	66,502	68,538
Other	17,015	13,669
Total deferred tax liabilities	1,718,014	158,897
Net deferred tax asset (liability)	(934,702)	353,781
Current asset (liability)	42,051	(7,775)
Non-current deferred tax asset (liability)	$ (976,753)	$ 361,556

Schedule Of Unrecognized Tax Benefits

Balance at January 1, 2009	$ 4,878
Additions based on tax positions related to the current year	1,593
Additions for tax positions of prior years	205
Reductions for tax positions of prior years	(6)
Balance at December 31, 2009	6,670
Additions based on tax positions related to the current year	1,493
Additions for tax positions of prior years	85
Reductions for tax positions of prior years	(3,830)
Balance at December 31, 2010	4,418
Additions based on tax positions related to the current year	1,626
Additions for tax positions of prior years	2,754
Balance at December 31, 2011	$ 8,798

- Definition

Tabular disclosure of tax positions taken in the tax returns filed or to be filed for which it is more likely than not that the tax position will not be sustained upon examination by taxing authorities (i.e., uncertain tax positions) and other types of income tax contingencies, including: (1) the policy on classification of interest and penalties; (2) a tabular reconciliation of the total amounts of unrecognized tax benefits at the beginning and end of the period; the total amount(s) of: (3) unrecognized tax benefits that, if recognized, would affect the effective tax rate, and (4) interest and penalties recognized in each of the income statement and balance sheet; (5) for positions for which it is reasonably possible that the total amounts unrecognized will significantly change within 12 months of the reporting date the: (i) nature of the uncertainty, (ii) nature of the event that could occur that would cause the change, and (iii) an estimate of the range of the reasonably possible change or a statement that an estimate of the range cannot be made; and (6) a description of tax years that remain subject to examination by major tax jurisdictions.

+ References + Details

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2011

Fair Value Measurements [Abstract]

Summary Of Financial Assets And Liabilities Accounted For At Fair Value


	Fair Value at December 31, 2011
	Total		Level 1		Level 2		Level 3
	(In thousands)
Assets:
Investments in equity securities	$	7,540	$	7,540	$	—	$	—
Derivatives	24,129		12,361		1,450		10,318
Total assets	$	31,669	$	19,901	$	1,450	$	10,318
Liabilities:
Derivatives	$	7,828	$	—	$	3,721	$	4,107

Summary Of Change In The Fair Values Of Financial Instruments Categorized As Level 3


		Year Ended December 31, 2011
	(In thousands)
Balance, beginning of period		$	9,183
Realized and unrealized losses recognized in earnings, net		(16,727		)
Realized and unrealized losses recognized in other comprehensive income, net		(4,122		)
Purchases		23,867
Issuances		(2,160		)
Settlements		(3,830		)
Balance, end of period		$	6,211

- Definition

Tabular disclosure of the fair value measurement of assets using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes during the period attributable to the following: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets) and gains or losses recognized in other comprehensive income, and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (2) purchases, sales, issuances, and settlements (each type disclosed separately); and (3) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs), by class of asset.

+ References + Details

- Definition

Tabular disclosure of the fair value measurement of assets and liabilities which includes [financial] instruments measured at fair value that are classified in stockholders' equity. Such assets and liabilities may be measured on a recurring or nonrecurring basis. The disclosures which may be required or desired include: (1) for assets and liabilities measured on a recurring basis, disclosure may include: (a) the fair value measurements at the reporting date; (b) the level within the fair value hierarchy in which the fair value measurements in their entirety fall, segregating fair value measurements using quoted prices in active markets for identical assets or liabilities (Level 1), significant other observable inputs (Level 2), and significant unobservable inputs (Level 3); (c) for fair value measurements using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes during the period attributable to the following: (i) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets), and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (ii) purchases, sales, issuances, and settlements (net); (iii) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs); (d) the amount of the total gains or losses for the period in subparagraph (c) (i) above included in earnings (or changes in net assets) that are attributable to the change in unrealized gains or losses relating to those assets and liabilities still held at the reporting date and a description of where those unrealized gains or losses are reported in the statement of income (or activities); (e) the valuation technique(s) used to measure fair value and a discussion of changes in valuation techniques, if any, during the period and (2) for assets and liabilities that are measured at fair value on a nonrecurring basis (for example, impaired assets) disclosure may include, in addition to (a) above: (a) the reasons for the fair value measurements recorded; (b) the same as (b) above; (c) for fair value measurements using significant unobservable inputs (Level 3), a description of the inputs and the information used to develop the inputs; and (d) the valuation technique(s) used to measure fair value and a discussion of changes, if any, in the valuation technique(s) used to measure similar assets and/or liabilities in prior periods. Where the quoted price in an active market for the identical liability is not available, the Level 1 input is the quoted price of an identical liability when traded as an asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 10
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 157
-Paragraph 32
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 157
-Paragraph 33
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 157
-Paragraph 6
-Footnote 4
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19190-110258

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19279-110258

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19296-110258

+ Details

Asset Retirement Obligations (Tables)

12 Months Ended

Dec. 31, 2011

Asset Retirement Obligations [Abstract]

Schedule Of Asset Retirement Obligations


	Year Ended December 31
	2011	2010
	(In thousands)
Balance at January 1 (including current portion)	$ 343,119	$ 310,409
Accretion expense	33,601	26,615
Obligations incurred or acquired	115,019	—
Adjustments to the liability from changes in estimates	11,176	8,934
Liabilities settled	(29,012)	(2,839)
Balance at December 31	$ 473,903	$ 343,119
Current portion included in accrued expenses	(27,119)	(8,862)
Noncurrent liability	$ 446,784	$ 334,257

Accrued Workers' Compensation (Tables)

12 Months Ended

Dec. 31, 2011

Accrued Workers Compensation [Line Items]

Workers' Compensation Expense


	Year Ended December 31
	2011	2010	2009
	(In thousands)
Self-insured occupational disease benefits:
Service cost	$ 2,059	$ 727	$ 531
Interest cost	1,799	675	558
Net amortization	(493)	(1,860)	(2,879)
Total occupational disease	3,365	(458)	(1,790)
Traumatic injury claims and assessments	16,979	9,263	8,904
Total workers' compensation expense	$ 20,344	$ 8,805	$ 7,114

Workers' Compensation [Member]

Accrued Workers Compensation [Line Items]

Schedule Of Changes in Projected Benefit Obligations


	December 31
	2011	2010
	(In thousands)
Beginning of year obligation	$ 17,412	$ 9,702
Service cost	2,059	727
Interest cost	1,799	675
Actuarial loss	7,081	6,993
Benefit and administrative payments	(1,097)	(685)
Acquisition of ICG	26,930	—
Net obligation at end of year	$ 54,184	$ 17,412

Schedule of Occupational Disease Obligation


	Year Ended December 31
	2011	2010	2009
Weighted average assumptions:
Discount rate	5.10%	5.96%	6.11%
Cost escalation rate	3.00%	3.00%	3.00%

Schedule Of Amounts Recognized In Balance Sheet


	December 31
	2011	2010
	(In thousands)
Occupational disease costs	$ 54,184	$ 17,412
Traumatic and other workers' compensation claims	29,430	24,537
Total obligations	83,614	41,949
Less amount included in accrued expenses	11,666	6,659
Noncurrent obligations	$ 71,948	$ 35,290

Employee Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2011

Employee Benefit Plans [Abstract]

Schedule Of Defined Benefit Plans Disclosures


	Pension Benefits		Other Postretirement Benefits
	2011	2010	2011	2010
	(In thousands)
CHANGE IN BENEFIT OBLIGATIONS
Benefit obligations at January 1	$ 297,707	$ 280,693	$ 39,633	$ 46,445
Service cost	16,490	15,870	3,917	1,509
Interest cost	16,253	15,822	3,279	2,083
Plan amendments	(3,235)	(92)	(55,542)	—
Benefits paid	(18,848)	(15,924)	(1,669)	(1,845)
Acquisition of ICG	—	—	48,441	—
Other-primarily actuarial loss (gain)	25,584	1,338	7,070	(8,559)
Benefit obligations at December 31	$ 333,951	$ 297,707	$ 45,129	$ 39,633
CHANGE IN PLAN ASSETS
Value of plan assets at January 1	$ 247,713	$ 211,899	$ —	$ —
Actual return on plan assets	9,443	34,401	—	—
Employer contributions	46,766	17,337	1,669	1,845
Benefits paid	(18,848)	(15,924)	(1,669)	(1,845)
Value of plan assets at December 31	$ 285,074	$ 247,713	$ —	$ —
Accrued benefit cost	$ (48,877)	$ (49,994)	$ (45,129)	$ (39,633)
ITEMS NOT YET RECOGNIZED AS A COMPONENT OF NET PERIODIC BENEFIT COST
Prior service credit (cost)	$ 1,736	$ (1,310)	$ 62,920	$ 9,742
Accumulated gain (loss)	(68,302)	(39,099)	1,795	11,965
	$ (66,566)	$ (40,409)	$ 64,715	$ 21,707
BALANCE SHEET AMOUNTS
Current liability	$ (633)	$ (840)	$ (2,820)	$ (1,840)
Noncurrent liability	$ (48,244)	$ (49,154)	$ (42,309)	$ (37,793)
	$ (48,877)	$ (49,994)	$ (45,129)	$ (39,633)

Schedule Of Net Benefit Costs


	Pension Benefits			Other Postretirement Benefits
Year Ended December 31,	2011	2010	2009	2011	2010	2009
	(In thousands)
Service cost	$ 16,490	$ 15,870	$ 13,444	$ 3,917	$ 1,509	$ 2,954
Interest cost	16,253	15,822	15,946	3,279	2,083	3,667
Expected return on plan assets*	(21,812)	(19,392)	(17,719)	—	—	—
Amortization of prior service cost (credit)	(189)	173	193	(2,364)	(2,364)	2,161
Amortization of other actuarial losses (gains)	8,748	7,130	3,967	(3,100)	(2,918)	(2,897)
Curtailments	—	—	585	—	—	—
Net benefit cost	$ 19,490	$ 19,603	$ 16,416	$ 1,732	$ (1,690)	$ 5,885

____________

*	The Company does not fund its other postretirement benefit obligations.

Schedule Of Assumptions Used To Calculate Benefit Obligation


	Pension Benefits		Other Postretirement Benefits
	2011	2010	2011	2010
Weighted average assumptions:
Discount rate	4.91%	5.71%	4.52%	5.23%
Rate of compensation increase	3.39%	3.39%	N/A	N/A

Schedule Of Assumptions Used


	Pension Benefits			Other Postretirement Benefits
	2011	2010	2009	2011	2010	2009
Weighted average assumptions:
Discount rate	5.71%	5.97%	6.85%	5.23%	5.67%	6.85%/5.68%
Rate of compensation increase	3.39%	3.39%	3.39%	N/A	N/A	N/A
Expected return on plan assets	8.50%	8.50%	8.50%	N/A	N/A	N/A

Schedule Of Allocation Of Plan Assets


	Total		Level 1				Level 2		Level 3
	2011	2010		2011	2010	2011		2010		2011	2010
	(In thousands)
Equity securities:(A)
U.S. small-cap	$11,178	$10,647		$11,178	$10,647	$ —		$ —		$ —	$ —
U.S. mid-cap	50,264	46,851		23,474	21,163	26,790		25,688		—	—
U.S. large-cap	91,561	77,632		44,820	38,397	46,741		39,235		—	—
Non-U.S.	22,509	24,995		—	—	22,509		24,995		—	—
Fixed income securities:
U.S. government securities(B)	13,454	3,053		12,738	2,492	716		561		—	—
Non-U.S. government securities(C)	2,968	3,469		—	—	2,968		3,469		—	—
U.S. government asset and mortgage backed securities(D)	800	1,073		—	—	800		1,073		—	—
Corporate fixed income(E)	14,004	13,737		—	—	14,004		13,737		—	—
State and local government securities(F)	18,416	13,679		—	—	18,416		13,679		—	—
Other fixed income(G)	51,470	45,628		—	—	51,470		45,628		—	—
Short-term investments(H)	8,029	6,110		—	—	8,029		6,110		—	—
Other investments(I)	421	839		—	—	421		839		—	—
Total	$285,074	$247,713		$92,210	$72,699	$192,864		$175,014		$ —	$ —

____________

(A)	Equity securities includes investments in 1) common stock, 2) preferred stock and 3) mutual funds. Investments in common and preferred stocks are valued using quoted market prices multiplied by the number of shares owned. Investments in mutual funds are valued at the net asset value per share multiplied by the number of shares held as of the measurement date and are traded on listed exchanges.

(B)	U.S. government securities includes agency and treasury debt. These investments are valued using dealer quotes in an active market.

(C)	Non-U.S. government securities includes debt securities issued by foreign governments and are valued utilizing a price spread basis valuation technique with observable sources from investment dealers and research vendors.

(D)	U.S. government asset and mortgage backed securities includes government-backed mortgage funds which are valued utilizing an income approach that includes various valuation techniques and sources such as discounted cash flows models, benchmark yields and securities, reported trades, issuer trades and/or other applicable data.

(E)	Corporate fixed income is primarily comprised of corporate bonds and certain corporate asset-backed securities that are denominated in the U.S. dollar and are investment-grade securities. These investments are valued using dealer quotes.

(F)	State and local government securities include different U.S. state and local municipal bonds and asset backed securities, these investments are valued utilizing a market approach that includes various valuation techniques and sources such as value generation models, broker quotes, benchmark yields and securities, reported trades, issuer trades and/or other applicable data.

(G)	Other fixed income investments are actively managed fixed income vehicles that are valued at the net asset value per share multiplied by the number of shares held as of the measurement date.

(H)	Short-term investments include governmental agency funds, government repurchase agreements, commingled funds, and pooled funds and mutual funds. Governmental agency funds are valued utilizing an option adjusted spread valuation technique and sources such as interest rate generation processes, benchmark yields and broker quotes. Investments in governmental repurchase agreements, commingled funds and pooled funds and mutual funds are valued at the net asset value per share multiplied by the number of shares held as of the measurement date.

(I)	Other investments includes cash, forward contracts, derivative instruments, credit default swaps, interest rate swaps and mutual funds. Investments in interest rate swaps are valued utilizing a market approach that includes various valuation techniques and sources such as value generation models, broker quotes in active and non-active markets, benchmark yields and securities, reported trades, issuer trades and/or other applicable data. Forward contracts and derivative instruments are valued at their exchange listed price or broker quote in an active market. The mutual funds are valued at the net asset value per share multiplied by the number of shares held as of the measurement date and are traded on listed exchanges.

Summary Of Estimated Future Benefit Payments

	Pension Benefits	Other Postretirement Benefits
	(In thousands)
2012	$ 17,898	$ 3,411
2013	20,854	3,787
2014	22,803	4,060
2015	22,492	4,406
2016	26,185	4,694
Years 2017-2021	164,788	25,122
	$ 275,020	$ 45,480

- Definition

Tabular disclosure of one or more of the entity's defined benefit pension plans or one or more other defined benefit postretirement plans, separately for pension plans and other postretirement benefit plans including the entity's schedule of fair value of plan assets for defined benefit or other postretirement plans.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5, 6, 7
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 158
-Paragraph 4, 7, 16, 20, 21
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=6930749&loc=d3e4179-114921

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e2410-114920

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e2439-114920

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e2417-114920

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Stock Based Compensation And Other Incentive Plans (Tables)

12 Months Ended

Dec. 31, 2011

Stock Based Compensation And Other Incentive Plans [Abstract]

Schedule Of Stock Option Activity Under Incentive Plan

	Common Shares	Weighted Average Exercise Price	Aggregate Intrinsic Value	Average Contract Life
	(In thousands)		(In thousands)
Options outstanding at January 1	4,544	$ 25.18
Granted	728	32.18
Exercised	(199)	11.61
Canceled	(88)	23.74
Expired	(32)	52.69
Options outstanding at December 31	4,953	26.60	$ 4,107	5.76
Options exercisable at December 31	3,157	27.59	3,887	4.35

Changes In Stock Options Outstanding And Not Yet Vested And Related Grant-Date Fair Value Under The Incentive Plan

	Common Shares	Weighted Average Grant-Date Fair Value
	(In thousands)
Unvested options at January 1	1,901	$ 10.61
Granted	728	14.18
Vested	(746)	13.28
Canceled	(87)	10.35
Unvested options at December 31	1,796	10.96

Weighted Average Assumptions Used In Option Pricing


	Year Ended December 31
	2011	2010	2009
Weighted average grant-date fair value per share of options granted	$ 14.18	$ 9.43	$ 6.63
Assumptions (weighted average):
Risk-free interest rate	1.92%	2.16%	1.75%
Expected dividend yield	1.25%	1.99%	2.56%
Expected volatility	57.4%	57.1%	69.3%
Expected life (in years)	4.5	4.5	4.5

Restricted Stock And Restricted Stock Unit Activity And Weighted Average Grant-Date Fair Value


	Restricted Stock		Restricted Stock Units
	Common Shares	Weighted Average Grant-Date Fair Value	Common Shares	Weighted Average Grant-Date Fair Value
	(In thousands)		(In thousands)
Outstanding at January 1	74	$ 24.69	54	$ 52.69
Granted	140	30.42	—	—
Vested	(27)	39.77	(27)	52.69
Canceled	(5)	32.49	—	—
Outstanding at December 31	182	26.68	27	52.69

Risk Concentrations (Tables)

12 Months Ended

Dec. 31, 2011

Segments, Geographical Areas [Abstract]

Schedule of Revenue from External Customers Attributed to Foreign Countries by Geographic Area

	December 31, 2011
	(In thousands)
Europe	$ 427,514
South America	120,842
North America	97,255
Asia	61,308
Brokered sales	213,087
Total	$ 920,006

Earnings Per Common Share (Tables)

12 Months Ended

Dec. 31, 2011

Earnings Per Common Share [Abstract]

Earnings Per Share


	Year Ended December 31
	2011	2010	2009
	(In thousands)
Weighted average shares outstanding:
Basic weighted average shares outstanding	190,086	162,398	150,963
Effect of common stock equivalents under incentive plans	819	812	309
Diluted weighted average shares outstanding	190,905	163,210	151,272

Leases (Tables)

12 Months Ended

Dec. 31, 2011

Leases [Abstract]

Schedule Of Operating Lease And Royalties Future Minimum Payments

	Operating Leases	Royalties
	(In thousands)
2012	$ 28,903	$ 24,378
2013	27,610	25,595
2014	25,119	25,810
2015	17,641	27,565
2016	9,648	24,397
Thereafter	12,640	114,371
	$ 121,561	$ 242,116

- Definition

Tabular disclosure of a lessee's leasing arrangements including: (1) the basis on which contingent rental payments are determined, (2) the existence and terms of renewal or purchase options and escalation clauses, (3) restrictions imposed by lease arrangements, such as those concerning dividends, additional debt, and further leasing, (4) rent holidays, rent concessions, or leasehold improvement incentives and unusual provisions or conditions. Disclosure may also include the specific period used to amortize material leasehold improvements made at the inception of the lease or during the lease term. Additionally, for operating leases having initial or remaining noncancelable lease terms in excess of one year: (a) future minimum rental payments required as of the date of the latest balance sheet presented, in the aggregate and for each of the five succeeding fiscal years, (b) the total of minimum rentals to be received in the future under noncancelable subleases as of the date of the latest balance sheet presented, and (c) for all operating leases, rental expense for each period for which an income statement is presented, with separate amounts for minimum rentals, contingent rentals, and sublease rentals. Rental payments under leases with terms of a month or less that were not renewed need not be included.

+ References + Details

Segment Information (Tables)

12 Months Ended

Dec. 31, 2011

Segment Information [Abstract]

Schedule Of Operating Segment Results


	PRB	APP	WBIT		Other Operating Segments		Corporate, Other and Eliminations		Consolidated
	(In thousands)
December 31, 2011
Revenues	$ 1,646,947	$ 1,915,090		$ 672,766		$ 51,092		$ —		$ 4,285,895
Income (loss) from operations	180,730	283,404		119,665		(4,685)		(165,538)		413,576
Total assets	2,307,783	4,740,723		681,393		581,040		1,903,020		10,213,959
Depreciation, depletion and amortization	171,693	203,759		81,235		7,876		2,024		466,587
Amortization of acquired sales contracts, net	19,458	(39,988)		—		(1,539)		—		(22,069)
Capital expenditures	110,999	217,435		66,356		28,243		117,903		540,936
December 31, 2010
Revenues	$ 1,606,236	$ 1,042,490		$ 537,542		$ —		$ —		$ 3,186,268
Income from operations	146,555	193,943		58,082		—		(74,596)		323,984
Total assets	2,295,786	706,624		677,611		—		1,200,748		4,880,769
Depreciation, depletion and amortization	185,218	97,764		80,497		—		1,587		365,066
Amortization of acquired sales contracts, net	35,606	—		—		—		—		35,606
Capital expenditures	38,142	70,839		65,470		—		140,206		314,657
December 31, 2009
Revenues	$ 1,205,492	$ 829,895		$ 540,694		$ —		$ —		$ 2,576,081
Income from operations	82,341	105,241		29,722		—		(93,590)		123,714
Total assets	2,421,917	734,309		687,873		—		996,497		4,840,596
Depreciation, depletion and amortization	127,378	88,409		83,781		—		2,040		301,608
Amortization of acquired sales contracts, net	19,934	—		(311)		—		—		19,623
Capital expenditures	58,275	48,673		67,299		—		148,903		323,150

Reconciliation Statement Of Segment Income From Operations To Consolidated Income Before Income Taxes


	Year Ended December 31
	2011	2010	2009
	(In thousands)
Income from operations	$ 413,576	$ 323,984	$ 123,714
Interest expense	(230,186)	(142,549)	(105,932)
Interest income	3,309	2,449	7,622
Bridge financing costs related to ICG	(49,490)	—	—
Loss on early extinguishment of debt	(1,958)	(6,776)	—
Income before income taxes	$ 135,251	$ 177,108	$ 25,404

- Definition

Tabular disclosure of the profit or loss and total assets for each reportable segment. An entity discloses certain information on each reportable segment if the amounts (a) are included in the measure of segment profit or loss reviewed by the chief operating decision maker or (b) are otherwise regularly provided to the chief operating decision maker, even if not included in that measure of segment profit or loss.

+ References + Details

Quarterly Financial Information (Tables)

12 Months Ended

Dec. 31, 2011

Quarterly Financial Information [Abstract]

Quarterly Financial Information

	March 31	June 30	September 30	December 31
		(a)(b)	(a)(b)	(a)
	(In thousands, except per share data)
2011:
Revenues	$ 872,938	$ 985,528	$ 1,198,673	$ 1,228,756
Gross profit	129,773	171,440	118,974	153,280
Income from operations	102,238	95,354	76,256	139,728
Net income	55,874	6,630	9,121	71,215
Basic earnings per common share	0.34	0.04	0.04	0.34
Diluted earnings per common share	0.34	0.04	0.04	0.33

	March 31	June 30	September 30	December 31
		(c)	(d)
	(In thousands, except per share data)
2010:
Revenues	$ 711,874	$ 764,295	$ 874,705	$ 835,394
Gross profit	61,852	100,461	119,957	107,514
Income from operations	32,200	106,499	98,347	86,938
Net income (loss)	(1,770)	66,274	46,859	48,031
Basic earnings (loss) per common share	(0.01)	0.41	0.29	0.29
Diluted earnings (loss) per common share	(0.01)	0.41	0.29	0.29

Supplemental Condensed Consolidating Financial Information (Tables)

12 Months Ended

Dec. 31, 2011

Supplemental Condensed Consolidating Financial Information [Abstract]

Schedule Of Condensed Consolidating Statements Of Income

CONDENSED CONSOLIDATING STATEMENTS OF INCOME

Year Ended December 31, 2011

Parent/Issuer

Guarantor

Subsidiaries

Non-Guarantor

Subsidiaries

Eliminations

Consolidated

(In thousands)

Revenues	$ –	$2,024,168	$ 2,261,727	$ –	$ 4,285,895

Costs, expenses and other
Cost of sales	22,925	1,537,697	1,812,461	(105,173)	3,267,910
Depreciation, depletion and amortization	2,883	304,742	158,962	–	466,587
Amortization of acquired sales contracts, net	–	(41,527)	19,458	–	(22,069)
Selling, general and administrative expenses	74,591	13,860	37,839	(7,234)	119,056
Change in fair value of coal derivatives and coal trading activities, net	–	(2,907)	–	–	(2,907)
Acquisition and transition costs	54,676	–	–	–	54,676
Other operating (income) expense, net	(23,306)	(118,767)	18,732	112,407	(10,934)

	131,769	1,693,098	2,047,452	-	3,872,319

Income from investment in subsidiaries	556,448	–	–	(556,448)	–

Income from operations	424,679	331,070	214,275	(556,448)	413,576
Interest income (expense), net:
Interest expense	(256,220)	(5,062)	(43,728)	74,824	(230,186)
Interest income	16,282	759	61,092	(74,824)	3,309
	(239,938)	(4,303)	17,364	–	(226,877)

Other non-operating expense
Bridge financing costs related to ICG	(49,490)	-	-	-	(49,490)
Net loss resulting from early retirement of debt	–	(1,958)	-	–	(1,958)
	(49,490)	(1,958)	-	–	(51,448)

Income before income taxes	135,251	324,809	231,639	(556,448)	135,251
Benefit from income taxes	(7,589)	–	–	–	(7,589)

Net income	142,840	324,809	231,639	(556,448)	142,840
Less: Net income attributable to noncontrolling interest	(1,157)	–	–	–	(1,157)

Net income attributable to Arch Coal	$ 141,683	$ 324,809	$ 231,639	$(556,448)	$141,683

CONDENSED CONSOLIDATING STATEMENTS OF INCOME

Year Ended December 31, 2010

	Parent/Issuer	Guarantor Subsidiaries	Non-Guarantor Subsidiaries	Eliminations	Consolidated
	(In thousands)

Revenues	$ —	$ 1,137,980	$ 2,048,288	$ —	$ 3,186,268

Costs, expenses and other
Cost of sales	11,526	797,917	1,679,872	(93,503)	2,395,812
Depreciation, depletion and amortization	2,933	194,847	167,286	—	365,066
Amortization of acquired sales contracts, net	—	—	35,606	—	35,606
Selling, general and administrative expenses	79,580	7,355	38,496	(7,254)	118,177
Change in fair value of coal derivatives and coal trading activities, net	—	8,924	—	—	8,924
Gain on Knight Hawk transaction	—	(41,577)	—	—	(41,577)
Other operating (income) expense, net	(10,259)	(115,994)	5,772	100,757	(19,724)
	83,780	851,472	1,927,032	—	2,862,284
Income from investment in subsidiaries	393,366	—	—	(393,366)	—

Income from operations	309,586	286,508	121,256	(393,366)	323,984

Interest expense, net:
Interest expense	(143,606)	(2,763)	(64,463)	68,283	(142,549)
Interest income	11,128	456	59,148	(68,283)	2,449
	(132,478)	(2,307)	(5,315)	—	(140,100)
Other non-operating expense
Net loss resulting from early retirement of debt	—	—	(6,776)	—	(6,776)
	—	—	(6,776)	—	(6,776)

Income before income taxes	177,108	284,201	109,165	(393,366)	177,108
Provision for income taxes	17,714	—	—	—	17,714
Net income	159,394	284,201	109,165	(393,366)	159,394
Less: Net income attributable to noncontrolling interest	(537)	—	—	—	(537)
Net income attributable to Arch Coal	$ 158,857	$ 284,201	$ 109,165	$ (393,366)	$ 158,857

CONDENSED CONSOLIDATING STATEMENTS OF INCOME

Year Ended December 31, 2009

	Parent/Issuer	Guarantor Subsidiaries	Non-Guarantor Subsidiaries	Eliminations	Consolidated
	(In thousands)

Revenues	$ —	$ 924,692	$ 1,651,389	$ —	$ 2,576,081

Costs, expenses and other
Cost of sales	7,481	713,782	1,398,663	(49,211)	2,070,715
Depreciation, depletion and amortization	3,678	138,125	159,805	—	301,608
Amortization of acquired sales contracts, net	—	—	19,623	—	19,623
Selling, general and administrative expenses	49,672	7,504	46,563	(5,952)	97,787
Change in fair value of coal derivatives and coal trading activities, net	—	(12,056)	—	—	(12,056)
Acquisition and transition costs	13,726	—	—	—	13,726
Other operating (income) expense, net	(12,909)	(85,460)	4,170	55,163	(39,036)
	61,648	761,895	1,628,824	—	2,452,367
Income from investment in subsidiaries	165,183	—	—	(165,183)	—

Income from operations	103,535	162,797	22,565	(165,183)	123,714

Interest expense, net:
Interest expense	(92,371)	(2,442)	(70,668)	59,549	(105,932)
Interest income	14,240	720	52,211	(59,549)	7,622
	(78,131)	(1,722)	(18,457)	—	(98,310)

Income before income taxes	25,404	161,075	4,108	(165,183)	25,404
Benefit from income taxes	(16,775)	—	—	—	(16,775)
Net income	42,179	161,075	4,108	(165,183)	42,179
Less: Net income attributable to noncontrolling interest	(10)	—	—	—	(10)
Net income attributable to Arch Coal	$ 42,169	$ 161,075	$ 4,108	$ (165,183)	$ 42,169

Schedule Of Condensed Consolidating Balance Sheets

CONDENSED CONSOLIDATING BALANCE SHEETS

December 31, 2011

	Parent/Issuer	Guarantor Subsidiaries	Non-Guarantor Subsidiaries	Eliminations	Consolidated
	(In thousands)
ASSETS
Cash and cash equivalents	$ 61,375	$ 332	$ 76,442	$ –	$ 138,149
Restricted cash	10,322	–	–	–	10,322
Receivables	65,187	22,037	383,572	(1,617)	469,179
Inventories	–	207,050	170,440	–	377,490
Other	81,732	83,122	22,780	–	187,634
Total current assets	218,616	312,541	653,234	(1,617)	1,182,774
Property, plant and equipment, net	21,241	6,403,658	1,524,251	–	7,949,150
Investment in subsidiaries	8,805,731	–	–	(8,805,731)	–
Intercompany receivables	(1,457,864)	7,010	1,450,854	–	–
Note receivable from Arch Western	225,000	–	–	(225,000)	–
Other	184,266	884,613	13,156	–	1,082,035
Total other assets	7,757,133	891,623	1,464,010	(9,030,731)	1,082,035
Total assets	$ 7,996,990	$7,607,822	$ 3,641,495	(9,032,348)	$10,213,959
LIABILITIES AND STOCKHOLDERS' EQUITY
Accounts payable	$ 25,409	$ 175,196	$ 183,177	$ –	$ 383,782
Accrued expenses and other current liabilities	75,133	115,685	166,834	(1,617)	356,035
Current maturities of debt and short-term borrowings	172,564	1,987	106,300	–	280,851
Total current liabilities	273,106	292,868	456,311	(1,617)	1,020,668
Long-term debt	3,308,674	2,652	450,971		3,762,297
Note payable to Arch Coal	–	–	225,000	(225,000)	–
Asset retirement obligations	877	140,861	305,046	–	446,784
Accrued pension benefits	19,198	4,203	24,843	–	48,244
Accrued postretirement benefits other than pension	13,843	6,271	22,195	–	42,309
Accrued workers' compensation	17,272	48,111	6,565	–	71,948
Deferred income taxes	621,483	355,270	–	–	976,753
Other noncurrent liabilities	152,963	64,795	37,624	–	255,382
Total liabilities	4,407,416	915,031	1,528,555	(226,617)	6,624,385
Redeemable noncontrolling interest	11,534	–	–	–	11,534
Stockholders' equity	3,578,040	6,692,791	2,112,940	(8,805,731)	3,578,040
Total liabilities and stockholders' equity	$ 7,996,990	$7,607,822	$ 3,641,495	$ (9,032,348)	$10,213,959

CONDENSED CONSOLIDATING BALANCE SHEETS

December 31, 2010

	Parent/Issuer	Guarantor Subsidiaries	Non-Guarantor Subsidiaries	Eliminations	Consolidated
	(In thousands)
ASSETS
Cash and cash equivalents	$ 13,713	$ 64	$ 79,816	$ —	$ 93,593
Receivables	31,458	12,740	210,075	(1,953)	252,320
Inventories	—	85,196	150,420	—	235,616
Other	29,575	102,375	21,435	—	153,385
Total current assets	74,746	200,375	461,746	(1,953)	734,914
Property, plant and equipment, net	9,817	1,800,578	1,498,497	—	3,308,892
Investment in subsidiaries	4,555,233	—	—	(4,555,233)	—
Intercompany receivables	(1,807,902)	508,624	1,299,278	—	—
Note receivable from Arch Western	225,000	—	—	(225,000)	—
Other	481,345	344,698	10,920	—	836,963
Total other assets	3,453,676	853,322	1,310,198	(4,780,233)	836,963
Total assets	$ 3,538,239	$ 2,854,275	$ 3,270,441	$ (4,782,186)	$ 4,880,769
LIABILITIES AND STOCKHOLDERS' EQUITY
Accounts payable	$ 10,753	$ 65,793	$ 121,670	$ —	$ 198,216
Accrued expenses and other current liabilities	75,746	31,123	153,217	(1,953)	258,133
Current maturities of debt and short-term borrowings	14,093	—	56,904	—	70,997
Total current liabilities	100,592	96,916	331,791	(1,953)	527,346
Long-term debt	1,087,126	—	451,618	—	1,538,744
Note payable to Arch Coal	—	—	225,000	(225,000)	—
Asset retirement obligations	873	32,029	301,355	—	334,257
Accrued pension benefits	20,843	4,407	23,904	—	49,154
Accrued postretirement benefits other than pension	14,284	—	23,509	—	37,793
Accrued workers' compensation	15,383	13,805	6,102	—	35,290
Other noncurrent liabilities	51,187	22,135	36,912	—	110,234
Total liabilities	1,290,288	169,292	1,400,191	(226,953)	2,632,818
Redeemable noncontrolling interest	10,444	—	—	—	10,444
Stockholders' equity	2,237,507	2,684,983	1,870,250	(4,555,233)	2,237,507
Total liabilities and stockholders' equity	$ 3,538,239	$ 2,854,275	$ 3,270,441	$ (4,782,186)	$ 4,880,769

Schedule Of Condensed Consolidating Statements Of Cash Flows

CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS

Year Ended December 31, 2011

	Parent/Issuer	Guarantor Subsidiaries	Non-Guarantor Subsidiaries	Eliminations	Consolidated
		(In thousands)
Cash provided by (used in) operating activities	$ (561,704)	$801,201	$ 402,745	$ –	$ 642,242
Investing Activities
Acquisitions of businesses, net of cash acquired	(2,894,339)	–	–	–	(2,894,339)
Decrease in restricted cash	5,167	–	–	–	5,167
Capital expenditures	(12,809)	(353,441)	(174,686)	–	(540,936)
Proceeds from dispositions of property, plant and equipment	–	25,730	157	–	25,887
Additions to prepaid royalties	-	(25,982)	(3,975)	-	(29,957)
Purchases of investments and advances to affiliates	(633,534)	(33,553)	-	605,178	(61,909)
Consideration paid related to prior business acquisitions	(829)	–	–	–	(829)
Cash used in investing activities	(3,536,344)	(387,246)	(178,504)	605,178	(3,496,916)
Financing Activities
Proceeds from the issuance of senior notes	2,000,000	–	–	–	2,000,000
Proceeds from the issuance of common stock, net	1,267,933	–	–	–	1,267,933
Contributions from parent	–	605,178	–	(605,178)	–
Payments to retire debt	–	(605,178)	–	–	(605,178)
Net increase (decrease) in borrowings under lines of credit and commercial paper program	481,300	–	(56,904)	–	424,396
Net proceeds from other debt	5,334	–	–	–	5,334
Debt financing costs	(114,799)	–	(24)	–	(114,823)
Dividends paid	(80,748)	–	–	–	(80,748)
Issuance of common stock under incentive plans	2,316	–	–	–	2,316
Transactions with affiliates, net	584,374	(413,687)	(170,687)	–	–
Cash provided by (used in) financing activities	4,145,710	(413,687)	(227,615)	(605,178)	2,899,230
Increase (decrease) in cash and cash equivalents	47,662	268	(3,374)	–	44,556
Cash and cash equivalents, beginning of period	13,713	64	79,816	–	93,593
Cash and cash equivalents, end of period	$ 61,375	$ 332	$ 76,442	$ –	$ 138,149

CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS

Year Ended December 31, 2010

	Parent/Issuer	Guarantor Subsidiaries	Non-Guarantor Subsidiaries	Consolidated
	(In thousands)
Cash provided by (used in) operating activities	$ (238,736)	$ 503,766	$ 432,117	$ 697,147
Investing Activities
Capital expenditures	(4,814)	(198,243)	(111,600)	(314,657)
Proceeds from dispositions of property, plant and equipment	—	251	79	330
Additions to prepaid royalties	—	(24,381)	(2,974)	(27,355)
Purchases of investments and advances to affiliates	(40,421)	(5,764)	—	(46,185)
Consideration paid related to prior business acquisitions	(1,262)	—	—	(1,262)
Cash used in investing activities	(46,497)	(228,137)	(114,495)	(389,129)
Financing Activities
Proceeds from the issuance of senior notes	500,000	—	—	500,000
Payments to retire debt	—	—	(505,627)	(505,627)
Net decrease in borrowings under lines of credit and commercial paper program	(120,000)	—	(76,549)	(196,549)
Net proceeds from other debt	82	—	—	82
Debt financing costs	(12,022)	—	(729)	(12,751)
Dividends paid	(63,373)	—	—	(63,373)
Issuance of common stock under incentive plans	1,764			1,764
Contribution from noncontrolling interest	—	—	891	891
Transactions with affiliates, net	(61,760)	(275,629)	337,389	—
Cash provided by (used in) financing activities	244,691	(275,629)	(244,625)	(275,563)
Increase (decrease) in cash and cash equivalents	(40,542)	—	72,997	32,455
Cash and cash equivalents, beginning of period	54,255	64	6,819	61,138
Cash and cash equivalents, end of period	$ 13,713	$ 64	$ 79,816	$ 93,593

CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS

Year Ended December 31, 2009

	Parent/Issuer	Guarantor Subsidiaries	Non-Guarantor Subsidiaries	Consolidated
	(In thousands)
Cash provided by (used in) operating activities	$ (168,427)	$ 338,956	$ 212,451	$ 382,980
Investing Activities
Acquisitions of businesses, net of cash acquired	(768,819)	—	—	(768,819)
Capital expendiutres	(2,940)	(194,756)	(125,454)	(323,150)
Proceeds from dispositions of property, plant and equipment	—	734	91	825
Additions to prepaid royalties	—	(23,991)	(2,764)	(26,755)
Purchases of investments and advances to affiliates	(8,000)	(2,925)	—	(10,925)
Consideration paid related to prior business acquisitions	(4,767)	—	—	(4,767)
Reimbursement of deposits on equipment	—	—	3,209	3,209
Cash used in investing activities	(784,526)	(220,938)	(124,918)	(1,130,382)
Financing Activities
Proceeds from the issuance of senior notes	584,784	—	—	584,784
Proceeds from the sale of common stock, net	326,452	—	—	326,452
Net decrease in borrowings under lines of credit and commercial paper program	(85,000)	—	(815)	(85,815)
Net payments on other debt	(2,986)	—	—	(2,986)
Debt financing costs	(29,456)	—	(203)	(29,659)
Dividends paid	(54,969)	—	—	(54,969)
Issuance of common stock under incentive plans	84	—	—	84
Transactions with affiliates, net	200,562	(118,015)	(82,547)	—
Cash provided by (used in) financing activities	939,471	(118,015)	(83,565)	737,891
Increase (decrease) in cash and cash equivalents	(13,482)	3	3,968	(9,511)
Cash and cash equivalents, beginning of period	67,737	61	2,851	70,649
Cash and cash equivalents, end of period	$ 54,255	$ 64	$ 6,819	$ 61,138

Valuation And Qualifying Accounts (Tables)

12 Months Ended

Dec. 31, 2011

Valuation And Qualifying Accounts [Abstract]

Valuation And Qualifying Accounts

	Balance at Beginning of Year	Additions (Reductions) Charged to Costs and Expenses	Charged to Other Accounts	Deductions(a)	Balance at End of Year
	(In thousands)
Year ended December 31, 2011
Reserves deducted from asset accounts:
Other assets — other notes and accounts receivable	$ —	$ 17	$ —	$ —	$ 17
Current assets — supplies and inventory	12,701	1,755	—	1,349	13,107
Deferred income taxes	737	2,416	—	322	2,831
Year ended December 31, 2010
Reserves deducted from asset accounts:
Other assets — other notes and accounts receivable	$ 109	$ —	$ —	$ 109	$ —
Current assets — supplies and inventory	13,406	1,962	—	2,667	12,701
Deferred income taxes	1,120	(383)	—	—	737
Year ended December 31, 2009
Reserves deducted from asset accounts:
Other assets — other notes and accounts receivable	$ 225	$ (17)	$ —	$ 99	$ 109
Current assets — supplies and inventory	12,760	1,302	—	656	13,406
Deferred income taxes	395	725	—	—	1,120

____________

(a)	Reserves utilized, unless otherwise indicated.

Accounting Policies (Details) $ in Thousands	12 Months Ended
Accounting Policies (Details) $ in Thousands	Dec. 31, 2011 USD ($) years	Dec. 31, 2010 USD ($)
Accounting Policies [Line Items]
Company's membership interest percentage in joint venture	99.00%
Number of mining complexes operated	23
Net book value of leased coal interests \| $	$ 10,868,694	$ 5,792,945
Minimum useful lives lease agreements	10
Minimum useful lives lease agreements	50
Incurred financing fees \| $	$ 90,500	37,600
Unamortized deferred financing costs, current \| $	$ 15,800	9,600
Buildings And Leasehold Improvements [Member]
Accounting Policies [Line Items]
Minimum useful life of mining equipment	10
Maximum useful life of mining equipment	30
Exploration And Production Equipment [Member]
Accounting Policies [Line Items]
Minimum useful life of mining equipment	5
Maximum useful life of mining equipment	32
Mining Properties And Mineral Rights [Member]
Accounting Policies [Line Items]
Net book value of leased coal interests \| $	$ 1,600,000	$ 1,600,000

Property Transactions (Details) Unit1 in Millions, $ in Millions	Dec. 31, 2011 USD ($)	Dec. 14, 2011 USD ($)	Mar. 18, 2010 USD ($)	Nov. 12, 2009 USD ($)
Montana Otter Creek [Member]
Property, Plant and Equipment [Line Items]
Mining operations purchase price			$ 85.8
Great Northern Properties Limited Partnership [Member]
Property, Plant and Equipment [Line Items]
Mining operations purchase price				$ 73.1
South Hilight [Member]
Property, Plant and Equipment [Line Items]
Mining operations purchase price		$ 300.0
Reserves [Member] \| Montana Otter Creek [Member]
Property, Plant and Equipment [Line Items]
Coal reserve in tons	1,400
Reserves [Member] \| South Hilight [Member]
Property, Plant and Equipment [Line Items]
Coal reserve in tons	222
Capital Additions [Member]
Property, Plant and Equipment [Line Items]
Unrecorded Unconditional Purchase Obligation Due Current	$ 23.4
Unrecorded Unconditional Purchase Obligation Due in Two Years	83.4
Unrecorded Unconditional Purchase Obligation Due in Three Years	67.3
Unrecorded Unconditional Purchase Obligation Due in Four Years	60.0
Unrecorded Unconditional Purchase Obligation Due in Five Years	$ 60.0

Business Combinations (Narrative) (Details) shares in Thousands, $ in Thousands, Unit1 in Millions		12 Months Ended
	Jun. 15, 2011	Dec. 31, 2011 USD ($) shares	Dec. 31, 2010 USD ($)	Dec. 31, 2009 USD ($) shares	Oct. 01, 2009 USD ($)
Business Acquisition [Line Items]
Proceeds from the issuance of common stock, net		$ 1,267,933		$ 326,452
Number of shares sold \| shares		48,705		19,550
Proceeds from issuance of aggregate principal amount of senior notes		$ 2,000,000	$ 500,000	$ 584,784
Revenues related to the acquired operations included in the statement of income since acquisition		606,900
Income before income taxes related to the acquired operations included in the statement of income since acquisition			$ 14,600
Restricted cash		$ 10,300
Number Of Mining Complexes - Appalachia [Member]
Business Acquisition [Line Items]
Number of mining complexes operated	12
Number of mining complexes being developed	one
Number Of Mining Complexes - Illinois [Member]
Business Acquisition [Line Items]
Number of mining complexes operated	one
Jacobs Ranch Mining Operations [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Purchase Price					$ 768,800
Tons Of Coal					345

Business Combinations (Summary Of Purchase Price Allocation) (Details) - USD ($) $ in Thousands		12 Months Ended
	Jun. 15, 2011	Dec. 31, 2011	Dec. 31, 2009	Dec. 31, 2010
Business Acquisition [Line Items]
Acquisitions of businesses, net of cash acquired	$ 2,894,400	$ 2,894,339	$ 768,819
Restricted cash	15,500
Receivables	113,200
Inventories	91,000
Net property, plant and equipment, including mineral rights	4,582,600
Goodwill	480,300
Other assets	35,900
Accounts payable	(86,000)
Other accrued expenses and current liabilities	(59,100)
Debt	(604,800)
Litigation accrual	(108,900)
Accrued postretirement benefits	(47,700)
Asset retirement obligation	(112,700)
Coal Supply Agreement Obligation Net		$ 96,998		$ 26,041
Coal supply agreements, net				$ (6,036)
Deferred income taxes, net	(1,278,900)
Other	(35,000)
Net tangible and intangible assets acquired	2,894,400
ICG [Member]
Business Acquisition [Line Items]
Coal Supply Agreement Obligation Net	$ 91,000

Business Combinations (Summary Of Unaudited Pro Forma) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Business Combinations [Abstract]
Revenues	$ 1,228,756	$ 1,198,673	$ 985,528	$ 872,938	$ 835,394	$ 874,705	$ 764,295	$ 711,874	$ 4,285,895	$ 3,186,268	$ 2,576,081
Total revenues pro forma									4,825,600	4,299,900
Income (loss) before income taxes									135,251	177,108	$ 25,404
Income (loss) before income taxes pro forma									$ 113,500	$ (1,200)

Business Combination (Schedule Of Costs And Expenses Reflected In The Income Before Income Taxes) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2011 USD ($)
Business Combinations [Abstract]
Costs of completing the acquisition	$ 31,600
Severance costs	15,800
Write off of acquired assets	7,300
Bridge financing fees	49,490
Total cost and expenses	$ 104,200

- Definition

The charge against earnings in the period, comprised of costs associated with restructuring activities not otherwise specified in the taxonomy pursuant to a duly authorized plan, excluding a discontinued operation as defined by generally accepted accounting principles. Costs of such activities include those for one-time termination benefits, termination of an operating lease or other contract, consolidating or closing facilities, and relocating employees, but excludes costs associated with the retirement of a long-lived asset and severance costs associated with established compensation plans.

+ References + Details

- Definition

The charge against earnings in the period for known and estimated costs of termination benefits provided to current employees that are involuntarily terminated under a benefit arrangement associated with exit from or disposal of business activities or restructurings pursuant to a duly authorized plan, excluding costs or losses pertaining to an entity newly acquired in a business combination or a discontinued operation as defined by generally accepted accounting principles and costs associated with one-time termination benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 5
-Section P
-Subsection 3, 4

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FAS146-1
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5-8
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 112
-Paragraph 7
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 146
-Paragraph 8-13, 20
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 5.P.3)
-URI http://asc.fasb.org/extlink&oid=6394695&loc=d3e140864-122747

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB TOPIC 5.P.4(b))
-URI http://asc.fasb.org/extlink&oid=6394695&loc=d3e140904-122747

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)(10)
-URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920

+ Details

Goodwill (Narrative) (Details) - USD ($) $ in Thousands	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Goodwill [Line Items]
Goodwill	$ 596,103	$ 114,963	$ 113,701	$ 46,832
Powder River Basin Segment [Member]
Goodwill [Line Items]
Goodwill	115,800
Appalachia Segment [Member]
Goodwill [Line Items]
Goodwill	$ 480,300

- Definition

Carrying amount as of the balance sheet date, which is the cumulative amount paid and (if applicable) the fair value of any noncontrolling interest in the acquiree, adjusted for any amortization recognized prior to the adoption of any changes in generally accepted accounting principles (as applicable) and for any impairment charges, in excess of the fair value of net assets acquired in one or more business combination transactions.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 142
-Paragraph 45
-Subparagraph e
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 142
-Paragraph 43
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141R
-Paragraph 68
-Subparagraph l
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6905597&loc=d3e13816-109267

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141R
-Paragraph 72
-Subparagraph d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 142
-Paragraph 45
-Subparagraph e
-Clause 1
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141R
-Paragraph 34
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Goodwill (Schedule Of Goodwill) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Goodwill [Line Items]
Goodwill, Beginning Balance	$ 114,963	$ 113,701	$ 46,832
Consideration paid related to prior business acquisitions	829	1,262	4,767
Goodwill, Ending Balance	596,103	114,963	113,701
Parent/Issuer [Member]
Goodwill [Line Items]
Consideration paid related to prior business acquisitions	829	$ 1,262	4,767
Jacobs Ranch [Member]
Goodwill [Line Items]
Acquisition during period			$ 62,102
ICG [Member]
Goodwill [Line Items]
Acquisition during period	$ 480,311

- Definition

+ References

+ Details

Debt And Financing Arrangements (Narrative) (Details)				12 Months Ended
Debt And Financing Arrangements (Narrative) (Details)	Jul. 14, 2011 USD ($)	Jun. 15, 2011 USD ($)	Sep. 08, 2010 USD ($)	Dec. 31, 2012 USD ($) years	Dec. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)	Dec. 31, 2009 USD ($)	Dec. 12, 2011 USD ($)	Jun. 14, 2011 USD ($)
Debt Instrument [Line Items]
Restricted cash					$ 10,322,000
Accrued interest					213,697,000	$ 134,866,000	$ 76,801,000
Debt assumed in acquisition		$ 604,800,000
Net loss resulting from early retirement of debt					$ 1,958,000	6,776,000
Weighted-average interest rate					3.04%
Letters of credit outstanding, amount					$ 146,600,000
Incurred financing fees					90,500,000	37,600,000
Line of credit facility, remaining borrowing capacity					$ 901,400,000
Debt Instrument covenant terms					<div class="MetaData"> <p style="text-align: justify; line-height: 94%; text-indent: 11pt; margin: 0in 0in 0pt; font-family: 'Times New Roman','serif'; font-size: 12pt;" class="MsoNormal"><font style="line-height: 94%; font-size: 10pt;" class="_mt">Terms of the Company's credit facilities and leases contain financial and other covenants that limit the ability of the Company to, among other things, acquire, dispose, merge or consolidate assets; incur additional debt; pay dividends and make distributions or repurchase stock; make investments; create liens; issue and sell capital stock of subsidiaries; enter into restrictions affecting the ability of restricted subsidiaries to make distributions, loans or advances to the Company; engage in transactions with affiliates and enter into sale and leaseback transactions. The terms also require the Company to, among other things, maintain various financial ratios and comply with various other financial covenants, including an interest coverage ratio test, as defined in the indentures. In addition, the covenants require the Company to pledge assets to collateralize the revolving credit facility. The assets pledged include equity interests in wholly-owned subsidiaries, certain real property interests, accounts receivable and inventory of the Company. Failure by the Company to comply with such covenants could result in an event of default, which, if not cured or waived, could have a material adverse effect on the Company. The Company complied with all financial covenants at December 31, 2011.</font></p></div>
Debt instrument, issuer					Arch Western Finance LLC ("Arch Western Finance"
Expected aggregate maturities in 2012					$ 280,900,000
Expected aggregate maturities in 2013					672,400,000
Expected aggregate maturities in 2014					0
Expected aggregate maturities in 2015					0
Expected aggregate maturities in 2016					$ 600,000,000
Failed to file registration statement, interest rate					one-quarter of one percent
7.00% Senior Notes Due June 15, 2019 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage					7.00%
Due date of senior notes					Jun. 15, 2019
7.25% Senior Notes Due 2021 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage					7.25%
2019 and 2021 Notes [Member]
Debt Instrument [Line Items]
Debt instrument, frequency of periodic payment					<font style="font-size: 10pt;" class="_mt">June 15 and December 15 of each year.</font>
Tender offer price upon change in control					101.00%
Issue costs related to notes					$ 44,200,000
Registration statement effective date deadline					June 13, 2012
Registration Rights agreement violation additional per annum penalty					0.25%
Registration Rights agreement violation maximum per annum penalty					1.00%
Registration Rights agreement violation per annum penalty in first 90 days					0.25%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit borrowings outstanding					$ 375,000,000
Accounts Receivable Securitization Program [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate at Period End					0.73%
Maximum borrowing capacity					$ 250,000,000			$ 175,000,000
Line of credit facility, expiration date					December 11, 2012
Line of credit borrowings outstanding					$ 106,300,000
9.125% Senior Notes Due April 1, 2018 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage									9.125%
Restricted cash									$ 260,700,000
Accrued interest	$ 5,200,000
4.00% Convertible Senior Notes Due April 1, 2017 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage									4.00%
Debt assumed in acquisition									$ 298,500,000
Calculated conversion rate		2,614.6848
Principal amount increment for conversion		1,000
9.00% Convertible Senior Notes Due August 1, 2012 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage									9.00%
Debt assumed in acquisition									$ 1,700,000
Calculated conversion rate		2,392.73414
Principal amount increment for conversion		$ 1,000
ICG Debt [Member]
Debt Instrument [Line Items]
Debt instrument, convertible, latest date					August 17, 2011
Debt assumed in acquisition					$ 54,000,000
Net loss resulting from early retirement of debt					$ 2,000,000
6.75% Senior Notes Due July 1, 2013 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage					6.75%
Net loss resulting from early retirement of debt						6,800,000
Due date of senior notes					Jul. 01, 2013
Amount of debt redeemed			$ 500,000,000
Redemption premium on extinguishment of debt						5,600,000
Write off of Deferred Debt Issuance Cost						3,300,000
Debt Instrument, Unamortized Premium						2,100,000
Debt instrument, frequency of periodic payment					Interest is payable on the notes on January 1 and July 1 of each year.
Face value of senior notes					$ 450,000,000
Debt instrument initial issue price percentage of face amount					104.75%
Debt Instrument covenant terms					The terms of the senior notes contain restrictive covenants that limit Arch Western's ability to, among other things, incur additional debt, sell or transfer assets, and make certain investments.
Principal Outstanding Issued At Premium					$ 118,400,000	118,400,000
8.75% Senior Notes Due August 1, 2016 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage					8.75%
Incurred financing fees					$ 14,500,000
Due date of senior notes					Aug. 01, 2016
Debt instrument, frequency of periodic payment					Interest is payable on the notes on February 1 and August 1 of each year
Face value of senior notes					$ 600,000,000
Debt instrument initial issue price percentage of face amount					97.464%
Call premium					108.75%
Percentage of maximum redemption aggregate principal amount from equity proceeds					35.00%
7.25% Senior Notes Due October 10, 2020 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage					7.25%
Due date of senior notes					Oct. 01, 2020
Debt instrument, frequency of periodic payment					April 1 and October 1 of each year
6.75% Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage					6.75%
Secured Credit Facility [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity				$ 2,000,000,000
Line of credit facility, maturity term \| years				5
Line of credit facility, expiration date					June 14, 2016
Line of credit facility, unused capacity, commitment fee percentage					0.50%
Secured revolving credit facility maximum borrowing amount					$ 234,200,000	132,000,000
Incurred financing fees					21,100,000
Average borrowings					$ 234,200,000	$ 132,000,000
Prior to June 15, 2014 [Member] \| 7.00% Senior Notes Due June 15, 2019 [Member]
Debt Instrument [Line Items]
Call premium					107.00%
Prior to June 15, 2014 [Member] \| 7.25% Senior Notes Due 2021 [Member]
Debt Instrument [Line Items]
Call premium					107.25%
Prior to June 15, 2014 [Member] \| 2019 and 2021 Notes [Member]
Debt Instrument [Line Items]
Percentage of maximum redemption aggregate principal amount from equity proceeds					35.00%
June 15, 2015 Through June 14, 2016 [Member] \| 7.00% Senior Notes Due June 15, 2019 [Member]
Debt Instrument [Line Items]
Debt instrument redemption period					June 15, 2015 through June 14, 2016
Call premium					103.50%
June 15, 2016 Through June 14, 2017 [Member] \| 7.00% Senior Notes Due June 15, 2019 [Member]
Debt Instrument [Line Items]
Debt instrument redemption period					June 15, 2016 through June 14, 2017
Call premium					101.75%
June 15, 2016 Through June 14, 2017 [Member] \| 7.25% Senior Notes Due 2021 [Member]
Debt Instrument [Line Items]
Debt instrument redemption period					June 15, 2016 through June 14, 2017
Call premium					103.625%
June 15, 2017 And Beyond [Member] \| 7.00% Senior Notes Due June 15, 2019 [Member]
Debt Instrument [Line Items]
Debt instrument redemption period					on June 15, 2017
Call premium					100.00%
June 15, 2019 and Beyond [Member] \| 7.25% Senior Notes Due 2021 [Member]
Debt Instrument [Line Items]
Debt instrument redemption period					on June 15, 2019
Call premium					100.00%
June 15, 2017 Through June 14, 2018 [Member] \| 7.25% Senior Notes Due 2021 [Member]
Debt Instrument [Line Items]
Debt instrument redemption period					June 15, 2017 through June 14, 2018
Call premium					102.417%
June 15, 2018 Through June 14, 2019 [Member] \| 7.25% Senior Notes Due 2021 [Member]
Debt Instrument [Line Items]
Debt instrument redemption period					June 15, 2018 through June 14, 2019
Call premium					101.208%
Redeemable Between August 1, 2013 And July 31, 2014 [Member] \| 8.75% Senior Notes Due August 1, 2016 [Member]
Debt Instrument [Line Items]
Debt instrument redemption period					between August 1, 2013 and July 31, 2014
Call premium					104.375%
Redeemable Between August 1, 2014 And July 31, 2015 [Member] \| 8.75% Senior Notes Due August 1, 2016 [Member]
Debt Instrument [Line Items]
Debt instrument redemption period					between August 1, 2014 and July 31, 2015
Call premium					102.188%
August 1, 2015 And Beyond [Member]
Debt Instrument [Line Items]
Call premium					100.00%
Redeemable Between October 1, 2015 And September 30, 2016 [Member] \| 7.25% Senior Notes Due October 10, 2020 [Member]
Debt Instrument [Line Items]
Call premium					103.625%
Redeemable Between October 1, 2016 And September 30, 2017 [Member] \| 7.25% Senior Notes Due October 10, 2020 [Member]
Debt Instrument [Line Items]
Call premium					102.417%
Redeemable Between October 1, 2017 And September 30, 2018 [Member] \| 7.25% Senior Notes Due October 10, 2020 [Member]
Debt Instrument [Line Items]
Call premium					101.208%
Redeemable On Or After October 1, 2018 [Member] \| 7.25% Senior Notes Due October 10, 2020 [Member]
Debt Instrument [Line Items]
Call premium					100.00%
Redeemable Prior to October 1, 2013 [Member] \| 7.25% Senior Notes Due October 10, 2020 [Member]
Debt Instrument [Line Items]
Debt instrument redemption period					prior to October 1, 2013
Call premium					107.25%
Percentage of maximum redemption aggregate principal amount from equity proceeds					35.00%
Redeemable Prior To August 1, 2012 [Member] \| 8.75% Senior Notes Due August 1, 2016 [Member]
Debt Instrument [Line Items]
Debt instrument redemption period					prior to August 1, 2012
Repayment of Debt [Member] \| 9.125% Senior Notes Due April 1, 2018 [Member]
Debt Instrument [Line Items]
Subsequent event, senior notes redeemed	$ 251,400,000

Debt And Financing Arrangements (Schedule Of Debt) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2011	Jun. 14, 2011	Dec. 31, 2010
Debt Instrument [Line Items]
Commercial paper			$ 56,904,000
Indebtedness to banks under credit facilities	$ 481,300,000
Other	21,903,000		14,093,000
Total	4,043,148,000		1,609,741,000
Less current maturities of debt and short-term borrowings	280,851,000		70,997,000
Long-term debt	3,762,297,000		1,538,744,000
7.00% Senior Notes Due June 15, 2019 [Member]
Debt Instrument [Line Items]
Senior notes	$ 1,000,000,000
Senior notes interest rate	7.00%
Due date of senior notes	Jun. 15, 2019
7.25% Senior Notes Due June 15, 2021 [Member]
Debt Instrument [Line Items]
Senior notes	$ 1,000,000,000
Senior notes interest rate	7.25%
Due date of senior notes	Jun. 15, 2021
9.125% Senior Notes Due April 1, 2018 [Member]
Debt Instrument [Line Items]
Senior notes interest rate		9.125%
4.00% Convertible Senior Notes Due April 1, 2017 [Member]
Debt Instrument [Line Items]
Senior notes interest rate		4.00%
9.00% Convertible Senior Notes Due August 1, 2012 [Member]
Debt Instrument [Line Items]
Senior notes interest rate		9.00%
6.75% Senior Notes Due July 1, 2013 [Member]
Debt Instrument [Line Items]
Senior notes	$ 450,971,000		451,618,000
Face value of senior notes	$ 450,000,000
Senior notes interest rate	6.75%
Due date of senior notes	Jul. 01, 2013
8.75% Senior Notes Due August 1, 2016 [Member]
Debt Instrument [Line Items]
Senior notes	$ 588,974,000		587,126,000
Face value of senior notes	$ 600,000,000
Senior notes interest rate	8.75%
Due date of senior notes	Aug. 01, 2016
7.25% Senior Notes Due October 10, 2020 [Member]
Debt Instrument [Line Items]
Senior notes	$ 500,000,000		$ 500,000,000
Senior notes interest rate	7.25%
Due date of senior notes	Oct. 01, 2020

Acquired Sales Contracts (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2011 USD ($)
Acquired Sales Contracts [Abstract]
Coal supply agreement asset, purchase price allocation	$ 35.0
Coal supply agreement liability, purchase price allocation	126.0
Amortization expense (income) of acquired sales contracts, year 2012	18.5
Amortization expense (income) of acquired sales contracts, year 2013	5.2
Amortization expense (income) of acquired sales contracts, year 2014	3.3
Amortization expense (income) of acquired sales contracts, year 2015	12.7
Amortization expense (income) of acquired sales contracts, year 2016	$ 7.7

Acquired Sales Contracts (Schedule Of Acquired Sales Contracts) (Details) - USD ($) $ in Thousands	Dec. 31, 2011	Dec. 31, 2010
Acquired Finite-Lived Intangible Assets And Liabilities By Major Class [Line Items]
Acquired fair value, Assets	$ 149,457	$ 114,453
Acquired fair value, Liabilities	166,697	40,654
Accumulated amortization, Asset	(115,322)	(82,376)
Accumulated amortization, Liabilities	(69,699)	(14,613)
Total, Assets	34,135	32,077
Total, Liabilities	96,998	26,041
Net total, Assets		6,036
Net total, Liabilities	(62,863)
Coal supply agreement, Liabilities	38,441	5,615
Accrued Expenses and Other Current Liabilities [Member]
Acquired Finite-Lived Intangible Assets And Liabilities By Major Class [Line Items]
Coal supply agreement, Liabilities	38,441	5,615
Other Current Assets [Member]
Acquired Finite-Lived Intangible Assets And Liabilities By Major Class [Line Items]
Coal supply agreement, Assets	18,929	25,063
Other Noncurrent Liabilities [Member]
Acquired Finite-Lived Intangible Assets And Liabilities By Major Class [Line Items]
Coal supply agreement, Liabilities	58,557	20,426
Other Assets [Member]
Acquired Finite-Lived Intangible Assets And Liabilities By Major Class [Line Items]
Coal supply agreement, Assets	$ 15,206	$ 7,014

Accumulated Other Comprehensive Income (Loss) (Components Of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Accumulated Other Comprehensive Income (Loss) [Abstract]
OtherComprehensiveIncomeDerivativesQualifyingAsHedgesNetOfTaxPortionAttributableToParent	$ (4,729)	$ 2,921	$ 1,186	$ (45,249)
Derivative Instruments, before tax	(11,951)	2,711	72,553
Derivative Instruments, tax effect	4,301	(976)	(26,118)
OtherComprehensiveIncomeDerivativesQualifyingAsHedgesNetOfTaxPortionAttributableToParent	(4,729)	2,921	1,186	(45,249)
OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPortionAttributableToParent	(4,676)	(10,679)	(20,539)	(33,433)
Pension, Postretirement and Other Post-Employment Benefits, before tax	9,345	15,406	20,124
Pension, Postretirement and Other Post-Employment Benefits, tax effect	(3,342)	(5,546)	(7,230)
OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPortionAttributableToParent	(4,676)	(10,679)	(20,539)	(33,433)
OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent	1,455	1,341	(500)	(414)
Available-for-Sale Securities, before tax	176	2,877	(136)
Available-for-Sale Securities, tax effect	(62)	(1,036)	50
OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent	1,455	1,341	(500)	(414)
OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	(7,950)	(6,417)	(19,853)	(79,096)
Accumulated Other Comprehensive Loss, before tax	(2,430)	20,994	92,541
Accumulated Other Comprehensive Loss, tax effect	897	(7,558)	(33,298)
OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	$ (7,950)	$ (6,417)	$ (19,853)	$ (79,096)

Equity Investments And Membership Interests In Joint Ventures (Narrative) (Details) $ in Thousands	1 Months Ended			3 Months Ended	12 Months Ended
	Jan. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)	Jun. 30, 2010 USD ($)	Jun. 30, 2010 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)	Dec. 31, 2009 USD ($)	Jul. 31, 2011	May 31, 2010	Dec. 31, 2008 USD ($)
Schedule of Equity Method Investments [Line Items]
Nonmonetary Transaction, Gain (Loss) Recognized on Transfer				$ 41,600		$ 41,577
Investments in and Advances to Affiliates, at Fair Value, Period Increase (Decrease)					$ (6,646)	(8,375)	$ (2,239)
Investments in and Advances to Affiliates, at Fair Value, Gross Additions					43,489	87,405
Notes receivable from investees		$ 23,900			35,810	23,900
Future development costs, maximum limit					74,400
Equity investments		$ 177,451			225,605	$ 177,451	87,268			$ 87,761
Knight Hawk [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest		49.00%	42.00%	42.00%		49.00%			33.33%
Additional ownership interest			9.00%	9.00%
Nonmonetary Transaction, Gain (Loss) Recognized on Transfer			$ 41,600
Investments in and Advances to Affiliates, at Fair Value, Period Increase (Decrease)					(16,621)	$ (12,639)	(5,164)
Investments in and Advances to Affiliates, at Fair Value, Gross Additions		$ 26,600				77,637
Notes receivable from investees		1,700				1,700
Equity investments		131,250			$ 135,225	131,250	49,603			48,093
DKRW [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest					24.00%
Investments in and Advances to Affiliates, at Fair Value, Period Increase (Decrease)
Investments in and Advances to Affiliates, at Fair Value, Gross Additions
Interest Rate on Note Receivable					1.25%
Notes receivable from investees		18,100			$ 30,751	18,100
Equity investments		21,961			$ 19,715	21,961	23,589			25,124
DTA [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest					21.875%
Investments in and Advances to Affiliates, at Fair Value, Period Increase (Decrease)					$ 6,498	4,264	2,925
Investments in and Advances to Affiliates, at Fair Value, Gross Additions
Notes receivable from investees
Equity investments		14,472			$ 16,086	14,472	14,076			14,544
Tenaska [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest					35.00%
Investments in and Advances to Affiliates, at Fair Value, Period Increase (Decrease)
Investments in and Advances to Affiliates, at Fair Value, Gross Additions					5,500	9,768
Notes receivable from investees		4,100			$ 5,059	4,100
Future development costs, percentage					35.00%
Future development costs, maximum limit					$ 12,500
Equity investments		9,768			15,266	9,768
Millennium [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest	38.00%
Investments in and Advances to Affiliates, at Fair Value, Period Increase (Decrease)					3,477
Investments in and Advances to Affiliates, at Fair Value, Gross Additions	$ 25,000				25,000
Notes receivable from investees
Equity investments					26,324
Tongue River [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest								33.00%
Investments in and Advances to Affiliates, at Fair Value, Period Increase (Decrease)
Investments in and Advances to Affiliates, at Fair Value, Gross Additions					12,989
Notes receivable from investees
Equity investments					$ 12,989
Reserves [Member] \| Knight Hawk [Member]
Schedule of Equity Method Investments [Line Items]
Tons Of Coal			68,400,000	68,400,000
Goods and Services Exchanged for Equity Instrument [Member] \| Knight Hawk [Member]
Schedule of Equity Method Investments [Line Items]
Mineral Properties, Net			$ 12,100	$ 12,100

Equity Investments And Membership Interests In Joint Ventures (Schedule Of Equity Method Investments) (Details) - USD ($) $ in Thousands	1 Months Ended		12 Months Ended
	Jan. 31, 2011	Dec. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Schedule of Equity Method Investments [Line Items]
Beginning, Balance	$ 177,451		$ 177,451	$ 87,268	$ 87,761
Investments in affiliates			43,489	87,405
Advances to (distributions from) affiliates, net			(6,646)	(8,375)	(2,239)
Equity in comprehensive income (loss)			11,311	11,153	1,746
Ending, Balance		$ 177,451	225,605	177,451	87,268
Balance at December 31, 2010	23,900		23,900
Balance at December 31, 2011		23,900	35,810	23,900
Knight Hawk [Member]
Schedule of Equity Method Investments [Line Items]
Beginning, Balance	131,250		131,250	49,603	48,093
Investments in affiliates		26,600		77,637
Advances to (distributions from) affiliates, net			(16,621)	(12,639)	(5,164)
Equity in comprehensive income (loss)			20,596	16,649	6,674
Ending, Balance		131,250	135,225	131,250	49,603
Balance at December 31, 2010	1,700		1,700
Balance at December 31, 2011		1,700		1,700
DKRW [Member]
Schedule of Equity Method Investments [Line Items]
Beginning, Balance	21,961		21,961	23,589	25,124
Investments in affiliates
Advances to (distributions from) affiliates, net
Equity in comprehensive income (loss)			(2,246)	(1,628)	(1,535)
Ending, Balance		21,961	19,715	21,961	23,589
Balance at December 31, 2010	18,100		18,100
Balance at December 31, 2011		18,100	30,751	18,100
DTA [Member]
Schedule of Equity Method Investments [Line Items]
Beginning, Balance	14,472		14,472	14,076	14,544
Investments in affiliates
Advances to (distributions from) affiliates, net			6,498	4,264	2,925
Equity in comprehensive income (loss)			(4,884)	(3,868)	(3,393)
Ending, Balance		14,472	16,086	14,472	14,076
Balance at December 31, 2010
Balance at December 31, 2011
Tenaska [Member]
Schedule of Equity Method Investments [Line Items]
Beginning, Balance	9,768		9,768
Investments in affiliates			5,500	9,768
Advances to (distributions from) affiliates, net
Equity in comprehensive income (loss)			(2)
Ending, Balance		9,768	15,266	9,768
Balance at December 31, 2010	4,100		4,100
Balance at December 31, 2011		4,100	5,059	4,100
Millennium [Member]
Schedule of Equity Method Investments [Line Items]
Beginning, Balance
Investments in affiliates	25,000		25,000
Advances to (distributions from) affiliates, net			3,477
Equity in comprehensive income (loss)			(2,153)
Ending, Balance			26,324
Balance at December 31, 2010
Balance at December 31, 2011
Tongue River [Member]
Schedule of Equity Method Investments [Line Items]
Beginning, Balance
Investments in affiliates			12,989
Advances to (distributions from) affiliates, net
Equity in comprehensive income (loss)
Ending, Balance			12,989
Balance at December 31, 2010
Balance at December 31, 2011

Equity Investments And Membership Interests In Joint Ventures (Summarized Financial Information Of Equity Method Investments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Equity Investments And Membership Interests In Joint Ventures [Abstract]
Revenues	$ 184,358	$ 172,933	$ 166,152
Gross profit	19,495	25,203	15,426
Income from operations	13,180	20,243	1,611
Net income (loss)	6,788	16,015	$ (1,797)
Current assets	94,644	48,202
Noncurrent assets	331,848	276,125
Total assets	426,492	324,327
Current liabilities	51,674	39,237
Noncurrent liabilities	120,494	99,350
Equity	254,163	185,639
Noncontrolling interest	161	101
Total liabilities and equity	$ 426,492	$ 324,327

Inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2011	Dec. 31, 2010
Inventories [Abstract]
Coal	$ 206,517	$ 115,647
Repair parts and supplies	163,527	119,969
Work-in-process	7,446
Inventories	377,490	235,616
Repair parts and supplies stated net of an allowance for slow-moving and obsolete inventories	$ 13,100	$ 12,700

- Definition

The amount of the valuation account as of the balance sheet date which reduces the carrying amount of inventory to net realizable value; takes into consideration such factors as market value, excessive quantities based on expected sales, technological obsolescence, and shrinkage. May also provide for estimated product returns or price concessions pertaining to product cost.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 6
-Subparagraph a
-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 43
-Chapter 3
-Section A
-Paragraph 9
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 43
-Chapter 4
-Paragraph 14
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 43
-Chapter 4
-Paragraph 8, 9, 14
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 09
-Article 12

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.6(a))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 330
-SubTopic 10
-Section 35
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6386567&loc=d3e3927-108312

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 330
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB TOPIC 5.BB)
-URI http://asc.fasb.org/extlink&oid=6386940&loc=d3e100047-122729

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-09)
-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e24092-122690

+ Details

Derivative Instruments (Narrative) (Details) $ in Millions	12 Months Ended
Derivative Instruments (Narrative) (Details) $ in Millions	Dec. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)	Dec. 31, 2009 USD ($)
Derivative [Line Items]
Percent of diesel purchases hedged	82.00%
Net unrealized and realized gains (losses) related to trading portfolio	$ (3.5)	$ 2.1	$ 2.4
Gain on derivative contracts designated as hedge instruments in cash flow hedges to be reclassified from OCI into earnings during the next twelve months	$ 9.2
Minimum Purchase [Member]
Derivative [Line Items]
Gallons of diesel fuel purchased annually	80,000,000
Maximum Purchase [Member]
Derivative [Line Items]
Gallons of diesel fuel purchased annually	90,000,000
2012 [Member]
Derivative [Line Items]
Value of trading portfolio realized	$ (2.6)
2013 [Member]
Derivative [Line Items]
Value of trading portfolio realized	$ (1.8)
Heating Oil - Fuel Surcharges [Member]
Derivative [Line Items]
Quantities under derivative contracts, tons	19,100,000
Current Assets [Member]
Derivative [Line Items]
Current asset for the right to reclaim cash collateral	$ 12.4	$ 10.3
Heating Oil [Member] \| Heating Oil - Diesel Purchases [Member]
Derivative [Line Items]
Quantities under derivative contracts, tons	69,000,000

Derivative Instruments (Derivative For Risk Management Purposes) (Details) Unit1 in Thousands	Dec. 31, 2011
Coal Purchases [Member] \| One Year From Balance Sheet Date [Member]
Derivative [Line Items]
Quantities under derivative contracts, tons	254
Coal Purchases [Member] \| More Than One And Within Two Years From Balance Sheet Date [Member]
Derivative [Line Items]
Quantities under derivative contracts, tons
Coal Purchases [Member] \| More Than Two And Within Three Years From Balance Sheet Date [Member]
Derivative [Line Items]
Quantities under derivative contracts, tons
Coal Purchases [Member] \| More Than Three And Within Four Years From Balance Sheet Date [Member]
Derivative [Line Items]
Quantities under derivative contracts, tons
Coal Sales [Member] \| One Year From Balance Sheet Date [Member]
Derivative [Line Items]
Quantities under derivative contracts, tons	2,416
Coal Sales [Member] \| More Than One And Within Two Years From Balance Sheet Date [Member]
Derivative [Line Items]
Quantities under derivative contracts, tons	1,117
Coal Sales [Member] \| More Than Two And Within Three Years From Balance Sheet Date [Member]
Derivative [Line Items]
Quantities under derivative contracts, tons	1,440
Coal Sales [Member] \| More Than Three And Within Four Years From Balance Sheet Date [Member]
Derivative [Line Items]
Quantities under derivative contracts, tons	720

Derivative Instruments (Disclosure Of Fair Value Of Derivatives) (Details) - USD ($) $ in Thousands	Dec. 31, 2011	Dec. 31, 2010
Derivative [Line Items]
Asset Derivative	$ 42,263	$ 51,068
Liability Derivative	(25,962)	(27,349)
Effect of counterparty netting, Asset Derivative	(18,134)	(22,402)
Effect of counterparty netting, Liability Derivative	18,134	22,402
Net derivative assets as classified in the balance sheet	24,129	28,666
Net derivative liabilities as classified in the balance sheet	(7,828)	(4,947)
Net derivatives as classified in the balance sheet	16,301	23,719
Designated As Hedging Instrument [Member]
Derivative [Line Items]
Asset Derivative	10,106	15,484
Liability Derivative		(2,350)
Designated As Hedging Instrument [Member] \| Heating Oil - Diesel Purchases [Member]
Derivative [Line Items]
Asset Derivative	8,997	13,475
Liability Derivative
Designated As Hedging Instrument [Member] \| Coal [Member]
Derivative [Line Items]
Asset Derivative	1,109	2,009
Liability Derivative		(2,350)
Not Designated As Hedging Instrument [Member]
Derivative [Line Items]
Asset Derivative	32,157	35,584
Liability Derivative	(25,962)	(24,999)
Not Designated As Hedging Instrument [Member] \| Heating Oil - Fuel Surcharges [Member]
Derivative [Line Items]
Asset Derivative	1,797
Liability Derivative
Not Designated As Hedging Instrument [Member] \| Coal Held For Trading Purposes [Member]
Derivative [Line Items]
Asset Derivative	15,505	34,445
Liability Derivative	(19,927)	(24,087)
Not Designated As Hedging Instrument [Member] \| Coal [Member]
Derivative [Line Items]
Asset Derivative	14,855	1,139
Liability Derivative	$ (6,035)	$ (912)

Derivative Instruments (Net Derivatives As Reflected On The Balance Sheets) (Details) - USD ($) $ in Thousands	Dec. 31, 2011	Dec. 31, 2010
Derivative [Line Items]
Derivative assets	$ 42,263	$ 51,068
Net derivatives as reflected on the balance sheet	16,301	23,719
Coal [Member]
Derivative [Line Items]
Coal derivative assets	13,335	15,191
Coal derivative liabilities	(7,828)	(4,947)
Other Current Assets [Member] \| Heating Oil [Member]
Derivative [Line Items]
Derivative assets	$ 10,794	$ 13,475

- Definition

Fair values as of the balance sheet date for all assets resulting from contracts that meet the criteria of being accounted for as derivative instruments and which are expected to be converted into cash or otherwise disposed of within a year or the normal operating cycle, if longer, net of the effects of master netting arrangements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 10
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 43
-Section A
-Paragraph 4
-Chapter 3
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FIN39-1
-Paragraph 10A, 10B
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 4, 17
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13433-108611

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13495-108611

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 45
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Current Assets
-URI http://asc.fasb.org/extlink&oid=6509628

+ Details

- Definition

Fair values as of the balance sheet date of all liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments, and which are expected to be extinguished or otherwise disposed of within a year or the normal operating cycle, if longer, net of the effects of master netting arrangements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 43
-Chapter 3
-Section A
-Paragraph 7
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FIN39-1
-Paragraph 10A, 10B
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 4, 17
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Current Liabilities
-URI http://asc.fasb.org/extlink&oid=6509677

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
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-Paragraph 15
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-Publisher FASB
-Name Accounting Standards Codification
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958

+ Details

Derivatives (Effects Of Derivatives On Measures Of Financial Performance) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Derivative [Line Items]
Gain (Loss) Recognized in OCI (Effective Portion)	$ 4,208	$ 282	$ 3,957
Gains (Losses) Reclassified from OCI into Income (Effective Portion)	16,438	(2,367)	(69,235)
Coal Purchases [Member]
Derivative [Line Items]
Gain (Loss) Recognized in OCI (Effective Portion)	(2,009)	5,145	1,089
Gains (Losses) Reclassified from OCI into Income (Effective Portion)		(1,202)	(13,181)
Coal Sales [Member]
Derivative [Line Items]
Gain (Loss) Recognized in OCI (Effective Portion)	4,923	(4,714)	(7,441)
Gains (Losses) Reclassified from OCI into Income (Effective Portion)	1,572	(1,602)	(6,999)
Coal [Member] \| Change In Fair Value Of Coal Derivatives And Coal Trading Activities Net [Member]
Derivative [Line Items]
Derivatives Not Designated as Hedging Instruments, Gains (Losses), Unrealized	6,438	(10,991)	9,673
Gain on Derivatives Used in Fair Value Hedge Relationships			2,586
Coal [Member] \| Other Operating Income, Net [Member]
Derivative [Line Items]
Derivatives Not Designated as Hedging Instruments, Gain, Realized		4,542
Derivatives Not Designated as Hedging Instruments, Losses, Realized	(7)
Heating Oil - Diesel Purchases [Member]
Derivative [Line Items]
Gain (Loss) Recognized in OCI (Effective Portion)	1,294	(149)	10,309
Heating Oil - Diesel Purchases [Member] \| Coal Purchases [Member]
Derivative [Line Items]
Gains (Losses) Reclassified from OCI into Income (Effective Portion)	14,866	$ 437	(49,055)
Heating Oil - Fuel Surcharges [Member] \| Other Operating Income, Net [Member]
Derivative [Line Items]
Derivatives Not Designated as Hedging Instruments, Gains (Losses), Unrealized	$ (2,906)
Firm Commitments [Member] \| Change In Fair Value Of Coal Derivatives And Coal Trading Activities Net [Member]
Derivative [Line Items]
Loss on Hedged Items in Fair Value Hedge Relationships			$ (2,586)

Accrued Expenses And Other Current Liabilities (Accrued Expenses And Other Current Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2011	Dec. 31, 2010
Accrued Expenses And Other Current Liabilities [Abstract]
Payroll and employee benefits	$ 65,323	$ 51,327
Taxes other than income taxes	133,331	107,969
Interest	55,266	52,843
Coal Supply Agreement Liability	38,441	5,615
Workers' compensation	11,666	6,659
Asset retirement obligations	27,119	8,862
Other	17,061	12,136
Accrued expenses and other current liabilities, total	$ 348,207	$ 245,411

- Definition

Carrying value as of the balance sheet date of obligations incurred and payable for real and property taxes. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References + Details

- Definition

Carrying value as of the balance sheet date of [accrued] interest payable on all forms of debt, including trade payables, that has been incurred and is unpaid. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References + Details

- Definition

Carrying value as of the balance sheet date of obligations incurred through that date and payable arising from transactions not otherwise specified in the taxonomy. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References + Details

Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
Taxes (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Taxes [Abstract]
Stock options and other equity based compensation, tax expense (benefit)	$ (0.4)	$ (0.8)	$ 0.2
Operating loss carryforwards	779.1			$ 145.1
Operating loss carryforwards, expiration dates		expire between 2012 and 2031
Tax credit carryforward	151.4
Future cash tax benefits accrue	0.8	$ 1.3	4.8
Increases (decreases) in valuation allowance	2.1	(0.4)	$ 0.7
Interest and penalties accrued related to unrecognized tax benefits	0.8	0.6
Interest and penalties recognized	$ 0.2	$ 0.1

Taxes (Schedule Of Components Of Income Tax) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Taxes [Abstract]
Current, Federal	$ (20,164)	$ 34,304	$ 21,295
Current, State	1,212	2,283	864
Total current	(18,952)	36,587	22,159
Deferred, Federal	13,214	(18,506)	(39,492)
Deferred, State	(1,851)	(367)	558
Total deferred	11,363	(18,873)	(38,934)
Provision for (benefit from) income taxes	$ (7,589)	$ 17,714	$ (16,775)

- Definition

The component of income tax expense for the period representing amounts paid or payable (or refundable) as determined by applying the provisions of enacted federal tax law to the domestic taxable Income or Loss from continuing operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 109
-Paragraph 45
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-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Paragraph h
-Article 4

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-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 6
-Section I
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-Name Accounting Standards Codification
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-Name Accounting Standards Codification
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-Name Accounting Standards Codification
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-Name Statement of Financial Accounting Standard (FAS)
-Number 109
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+ Details

- Definition

The component of income tax expense for the period representing amounts of income taxes paid or payable (or refundable) for the period for all income tax obligations as determined by applying the provisions of relevant enacted tax laws to relevant amounts of taxable Income or Loss from continuing operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
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-Name Accounting Standards Codification
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-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 6
-Section I
-Subsection 7

+ Details

- Definition

The component of income tax expense for the period representing amounts paid or payable (or refundable) as determined by applying the provisions of enacted state and local tax law to relevant amounts of taxable Income or Loss from continuing operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
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-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Paragraph h
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-Publisher FASB
-Name Accounting Standards Codification
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-Name Statement of Financial Accounting Standard (FAS)
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 6
-Section I
-Subsection 7

+ Details

- Definition

The component of total income tax expense for the period comprised of the increase (decrease) during the period in the entity's domestic deferred tax assets and liabilities attributable to continuing operations as determined by applying the provisions of the federally enacted tax law.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Paragraph h
-Article 4

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Publisher FASB
-Name Accounting Standards Codification
-Glossary Deferred Tax Expense (or Benefit)
-URI http://asc.fasb.org/extlink&oid=6510177

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-Name Accounting Standards Codification
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-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 6
-Section I
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+ Details

- Definition

The component of income tax expense for the period representing the increase (decrease) in the entity's deferred tax assets and liabilities pertaining to continuing operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 95
-Paragraph 28
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-Publisher SEC
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-Glossary Deferred Tax Expense (or Benefit)
-URI http://asc.fasb.org/extlink&oid=6510177

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Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 6
-Section I
-Subsection 7

+ Details

- Definition

The component of total income tax expense for the period comprised of the increase (decrease) in the entity's state and local deferred tax assets and liabilities attributable to continuing operations as determined by applying the provisions of the applicable enacted tax laws.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Paragraph h
-Article 4

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+ Details

Taxes (Schedule Of Effective Income Tax Rate Reconciliation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Taxes [Abstract]
Income tax expense at statutory rate	$ 46,933	$ 61,800	$ 8,888
Percentage depletion allowance	(61,971)	(49,152)	(29,463)
State taxes, net of effect of federal taxes	(3,055)	2,299	(61)
Change in valuation allowance	2,416	(383)	725
Other, net	8,088	3,150	3,136
Provision for (benefit from) income taxes	$ (7,589)	$ 17,714	$ (16,775)

Taxes (Schedule Of Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Taxes [Abstract]
Alternative minimum tax credit carryforwards	$ 151,404	$ 170,592
Net operating loss carryforwards	324,393	102,355
Reclamation and mine closure	93,914	71,533
Advance royalties		38,557
Plant and equipment		19,846
Acquired sales contracts	44,717	20,120
Other	171,715	90,412
Gross deferred tax assets	786,143	513,415
Valuation allowance	(2,831)	(737)
Total deferred tax assets	783,312	512,678
Deferred tax liabilities, plant and equipment	1,566,769
Deferred development	67,728	76,690
Investment in tax partnerships	66,502	68,538
Other	17,015	13,669
Total deferred tax liabilities	1,718,014	158,897
Net deferred tax asset	(934,702)	353,781
Current liability	42,051	(7,775)
Long-term deferred tax asset	$ (976,753)	$ 361,556

Fair Value Measurements (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Fair Value Measurements [Line Items]
Fair value of senior notes and other long-term debt, including amounts classified as current	$ 4,200.0	$ 1,700.0
Level 3 [Member]
Fair Value Measurements [Line Items]
Net unrealized losses related to level 3 financial instruments	$ 13.1

Fair Value Measurements (Summary Of Financial Assets And Liabilities Accounted For At Fair Value) (Details) - USD ($) $ in Thousands	Dec. 31, 2011	Dec. 31, 2010
Assets:
Investments in equity securities	$ 7,540
Derivatives	24,129	$ 28,666
Total assets	31,669
Liabilities:
Derivatives	7,828	$ 4,947
Level 1 [Member]
Assets:
Investments in equity securities	7,540
Derivatives	12,361
Total assets	19,901
Liabilities:
Derivatives
Level 2 [Member]
Assets:
Investments in equity securities
Derivatives	1,450
Total assets	1,450
Liabilities:
Derivatives	3,721
Level 3 [Member]
Assets:
Derivatives	10,318
Total assets	10,318
Liabilities:
Derivatives	$ 4,107

- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

+ References + Details

- Definition

Fair values as of the balance sheet date of all assets resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements.

+ References + Details

- Definition

Fair values as of the balance sheet date of all liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements.

+ References + Details

Fair Value Measurements (Summary Of Change In The Fair Values Of Financial Instruments Categorized As Level 3) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2011 USD ($)
Fair Value Measurements [Abstract]
Balance, beginning of period	$ 9,183
Realized and unrealized losses recognized in earnings, net	(16,727)
Realized and unrealized losses recognized in other comprehensive income, net	(4,122)
Purchases	23,867
Issuances	(2,160)
Settlements	(3,830)
Balance, end of period	$ 6,211

Asset Retirement Obligations (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Asset Retirement Obligations [Line Items]
Liabilities settled	$ (29,012)	$ (2,839)
Surety bonds outstanding	263,000
Asset Retirement Obligations [Member]
Asset Retirement Obligations [Line Items]
Self-bonding obligations	$ 420,500

Asset Retirement Obligations (Schedule Of Asset Retirement Obligations) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Asset Retirement Obligations [Abstract]
Balance at January 1 (including current portion)	$ 343,119	$ 310,409
Accretion expense	33,601	26,615
Obligations incurred or acquired	115,019
Adjustments to the liability from changes in estimates	11,176	8,934
Liabilities settled	(29,012)	(2,839)
Balance at December 31	473,903	343,119
Current portion included in accrued expenses	(27,119)	(8,862)
Noncurrent liability	$ 446,784	$ 334,257

Accrued Workers' Compensation (Worker's Compensation Expense) (Details) - Workers' Compensation [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Accrued Workers Compensation [Line Items]
Service cost	$ 2,059	$ 727	$ 531
Interest cost	1,799	675	558
Net amortization	(493)	(1,860)	(2,879)
Total occupational disease	3,365	(458)	(1,790)
Traumatic injury claims and assessments	16,979	9,263	8,904
Total workers' compensation expense	$ 20,344	$ 8,805	$ 7,114

- Definition

The increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation due to the passage of time.

+ References + Details

- Definition

The actuarial present value of benefits attributed by the pension benefit formula to services rendered by employees during the period. The portion of the expected postretirement benefit obligation attributed to employee service during the period. The service cost component is a portion of the benefit obligation and is unaffected by the funded status of the plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 106
-Paragraph 518
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 87
-Paragraph 264
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph a, h
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (h)(1)
-URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Service Cost (Component of Net Periodic Pension Cost)
-URI http://asc.fasb.org/extlink&oid=6525008

+ Details

Accrued Workers' Compensation (Schedule Of Changes in Projected Benefit Obligations) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Accrued Workers Compensation [Line Items]
Accumulated gain (loss)	$ (5,500)	$ 2,000
Workers' Compensation [Member]
Accrued Workers Compensation [Line Items]
Benefit obligations at January 1	17,412	9,702
Service cost	2,059	727	$ 531
Interest cost	1,799	675	558
Actuarial loss	7,081	6,993
Benefit and administrative payments	(1,097)	(685)
Acquisition of ICG	26,930
Benefit obligations at December 31	54,184	$ 17,412	$ 9,702
Amortization of net gains (losses)	$ 1,100

Accrued Workers' Compensation (Schedule Of Assumptions Used) (Details) - Workers' Compensation [Member]	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Accrued Workers Compensation [Line Items]
Discount rate	5.10%	5.96%	6.11%
Cost escalation rate	3.00%	3.00%	3.00%

Accrued Workers' Compensation (Schedule Of Amounts Recognized In Balance Sheet) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Accrued Workers Compensation [Line Items]
Less amount included in accrued expenses	$ 11,666	$ 6,659
Noncurrent obligations	71,948	35,290
Workers' Compensation [Member]
Accrued Workers Compensation [Line Items]
Occupational disease costs	29,430	24,537
Total obligations	83,614	41,949
Less amount included in accrued expenses	11,666	6,659
Noncurrent obligations	71,948	35,290
Surety bonds and letters of credit outstanding	60,100
Occupational Disease [Member]
Accrued Workers Compensation [Line Items]
Occupational disease costs	$ 54,184	$ 17,412

Employee Benefit Plans (Narrative) (Details) $ in Thousands	12 Months Ended
Employee Benefit Plans (Narrative) (Details) $ in Thousands	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)	Dec. 31, 2009 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Amendment to benefit plan, adjustment to benefit obligation		$ 55,500		$ 21,000
Accumulated benefit obligation of pension plans		314,700	$ 280,400
Benefit obligation for the unfunded pension plan		8,200
Accumulated benefit obligation for the unfunded pension plan		$ 7,100
Defined benefit plan amortization period		5
Health care cost trend rate assumed		7.70%
Ultimate trend rate		4.50%
Defined Benefit Plan, Year that Rate Reaches Ultimate Trend Rate		2028
Effect of one-percentage-point increase in health care cost trend rate		$ 500
Effect of one-percentage-point decrease in health care cost trend rate		$ 400
Percentage of plan assets, equity securities		65.00%
Percentage of plan assets, fixed income securities		30.00%
Percentage of plan assets, cash		5.00%
Contributions to the pension plans	$ 24,500
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefit obligation, decrease in discount rate		4.91%	5.71%
Benefit obligations		$ 333,951	$ 297,707	280,693
Amortization of net prior service cost		(100)
Defined Benefit Plan, Amortization of Net Gains (Losses)		$ (14,300)
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefit obligation, decrease in discount rate		4.52%	5.23%
Benefit obligations		$ 45,129	$ 39,633	46,445
Amortization of net prior service cost		(12,000)
Defined Benefit Plan, Amortization of Net Gains (Losses)		400
Other Pension Plans, Postretirement or Supplemental Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Other postretirement benefits payments		$ 25,900	$ 18,100	$ 15,900
Post-Remeasurement [Member]
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefit obligation, decrease in discount rate				5.68%
Pre-Remeasurement [Member]
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefit obligation, decrease in discount rate				6.85%

Employee Benefit Plans (Schedule Of Defined Benefit Plans Disclosures) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Defined Benefit Plan Disclosure [Line Items]
Value of plan assets at January 1	$ 247,713
Value of plan assets at December 31	285,074	$ 247,713
Accumulated gain (loss)	5,500	(2,000)
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligations at January 1	297,707	280,693
Service cost	16,490	15,870	$ 13,444
Interest cost	16,253	15,822	15,946
Plan amendments	(3,235)	(92)
Benefits paid	(18,848)	(15,924)
Acquisition of ICG
Other-primarily actuarial loss (gain)	25,584	1,338
Benefit obligations at December 31	333,951	297,707	280,693
Value of plan assets at January 1	247,713	211,899
Actual return on plan assets	9,443	34,401
Employer contributions	46,766	17,337
Value of plan assets at December 31	285,074	247,713	211,899
Accrued benefit cost	(48,877)	(49,994)
Prior service credit (cost)	1,736	(1,310)
Accumulated gain (loss)	(68,302)	(39,099)
Total not yet recognized as a component of net periodic benefit cost	(66,566)	(40,409)
Current liability	(633)	(840)
Noncurrent liability	(48,244)	(49,154)
Pension and other postretirement defined benefit plans, liabilities	(48,877)	(49,994)
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligations at January 1	39,633	46,445
Service cost	3,917	1,509	2,954
Interest cost	3,279	2,083	3,667
Plan amendments	(55,542)
Benefits paid	(1,669)	(1,845)
Acquisition of ICG	48,441
Other-primarily actuarial loss (gain)	7,070	(8,559)
Benefit obligations at December 31	45,129	39,633	46,445
Value of plan assets at January 1
Actual return on plan assets
Employer contributions	1,669	1,845
Value of plan assets at December 31
Accrued benefit cost	(45,129)	(39,633)
Prior service credit (cost)	62,920	9,742
Accumulated gain (loss)	1,795	11,965
Total not yet recognized as a component of net periodic benefit cost	64,715	21,707
Current liability	(2,820)	(1,840)
Noncurrent liability	(42,309)	(37,793)
Pension and other postretirement defined benefit plans, liabilities	$ (45,129)	$ (39,633)

Employee Benefit Plans (Schedule Of Net Benefit Costs) (Details) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2011

Dec. 31, 2010

Dec. 31, 2009

Pension Benefits [Member]

Defined Benefit Plan Disclosure [Line Items]

Service cost

$ 16,490

$ 15,870

$ 13,444

Interest cost

16,253

15,822

15,946

Expected return on plan assets

^[1]

(21,812)

(19,392)

(17,719)

Amortization of prior service cost (credit)

(189)

173

193

Amortization of other actuarial (gains) losses

8,748

7,130

3,967

Curtailments

585

Net benefit cost

19,490

19,603

16,416

Capital Stock (Details) - USD ($) $ / shares in Units, $ in Thousands				7 Months Ended	12 Months Ended
	Jul. 08, 2011	Jun. 08, 2011	Aug. 06, 2009	Jul. 31, 2009	Dec. 31, 2011	Dec. 31, 2009	Jul. 31, 2011
Common stock issued					48,705,000	19,550,000
Proceeds from the sale of common stock					$ 1,267,933	$ 326,452
Stock repurchase authorized number					14,000,000
Outstanding shares available for repurchase					10,925,800
ICG [Member]
Common stock issued	700,000	48,000,000
Common stock public offering price		$ 27.00
Proceeds from the sale of common stock	$ 18,400				$ 1,250,000
Jacobs Ranch Mining Operations [Member]
Common stock issued			2,550,000	17,000,000
Common stock public offering price							$ 17.50
Proceeds from the sale of common stock			$ 326,500

Stock Based Compensation And Other Incentive Plans (Schedule Of Stock Option Activity Under Incentive Plan) (Details) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2011 USD ($) $ / shares shares	Dec. 31, 2010 $ / shares shares	Dec. 31, 2009 shares
Stock Based Compensation And Other Incentive Plans [Abstract]
Options outstanding at January 1 \| shares	4,544
Granted, Common Shares \| shares	728
Exercised, Common Shares \| shares	(199)	(155)	(13)
Cancelled, Common Shares \| shares	(88)
Expired, Common Shares \| shares	(32)
Options outstanding at December 31 \| shares	4,953	4,544
Options exercisable at December 31 \| shares	3,157
Options outstanding at January 1, Weighted Average Exercise Price \| $ / shares	$ 25.18
Granted, Weighted Average Exercise Price \| $ / shares	32.18
Exercised, Weighted Average Exercise Price \| $ / shares	11.61
Cancelled, Weighted Average Exercise Price \| $ / shares	23.74
Expired, Weighted Average Exercise Price \| $ / shares	52.69
Options outstanding at December 31, Weighted Average Exercise Price \| $ / shares	26.60	$ 25.18
Options exercisable at December 31, Weighted Average Exercise Price \| $ / shares	$ 27.59
Options outstanding at December 31, Aggregate Intrinsic Value \| $	$ 4,107
Options exercisable at December 31, Aggregate Intrinsic Value \| $	$ 3,887
Options outstanding at December 31, Average Contract Life	5.76
Options exercisable at December 31 , Average Contract Life	4.35

Stock Based Compensation And Other Incentive Plans (Changes In Stock Options Outstanding And Not Yet Vested And Related Grant-Date Fair Value Under The Incentive Plan) (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2011 shares
Stock Based Compensation And Other Incentive Plans [Abstract]
Unvested options at January 1	1,901
Granted, Common Shares	728
Vested, Common Shares	(746)
Cancelled, Common Shares	(87)
Unvested options at December 31	1,796
Unvested options at January 1, Weighted Average Grant-Date Fair Value	10.61
Granted , Weighted Average Grant-Date Fair Value	14.18
Vested, Weighted Average Grant-Date Fair Value	13.28
Canceled, Weighted Average Grant-Date Fair Value	10.35
Unvested options at December 31, Weighted Average Grant-Date Fair Value	10.96

Stock-Based Compensation And Other Incentive Plans (Weighted Average Assumptions Used In Option Pricing) (Details)	12 Months Ended
	Dec. 31, 2011 years $ / shares	Dec. 31, 2010 years $ / shares	Dec. 31, 2009 years $ / shares
Stock Based Compensation And Other Incentive Plans [Abstract]
Weighted average grant-date fair value per share of options granted \| $ / shares	$ 14.18	$ 9.43	$ 6.63
Risk-free interest rate	1.92%	2.16%	1.75%
Expected dividend yield	1.25%	1.99%	2.56%
Expected volatility	57.40%	57.10%	69.30%
Expected life (in years) \| years	4.5	4.5	4.5

Risk Concentrations (Details) $ in Thousands, T in Millions	12 Months Ended
Risk Concentrations (Details) $ in Thousands, T in Millions	Dec. 31, 2011 USD ($) T	Dec. 31, 2010 USD ($)	Dec. 31, 2009 USD ($)
Concentration Risk [Line Items]
Sales to customers in foreign countries	$ 920,000	$ 471,500	$ 194,400
Trade accounts receivable	380,595	208,060
Receivables	$ 469,179	$ 252,320
Tons of coal sold \| T	156.9
Percentage of tons sold	72.00%
Long-term contracts, life term, minimum (years)	one
Long term sales contract term, in years	to nine years
Electric Utilities [Member]
Concentration Risk [Line Items]
Percentage of total trade accounts receivable	69.00%	88.00%
Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Sales (including spot sales)	$ 266,800	$ 301,400	$ 278,800
Domestic And Foreign Steel Producers [Member]
Concentration Risk [Line Items]
Trade accounts receivable	$ 117,400	$ 24,900
Trade receivables, percentage	31.00%	12.00%
Domestic Electric Utilities [Member]
Concentration Risk [Line Items]
Receivables	$ 261,200	$ 183,100
Long-term Contracts [Member]
Concentration Risk [Line Items]
Percentage of total revenue	57.00%
Europe [Member]
Concentration Risk [Line Items]
Sales to customers in foreign countries	$ 427,514,000
South America [Member]
Concentration Risk [Line Items]
Sales to customers in foreign countries	120,842,000
North America [Member]
Concentration Risk [Line Items]
Sales to customers in foreign countries	97,255,000
Asia [Member]
Concentration Risk [Line Items]
Sales to customers in foreign countries	61,308,000
Brokered sales [Member]
Concentration Risk [Line Items]
Sales to customers in foreign countries	213,087,000
Total [Member]
Concentration Risk [Line Items]
Sales to customers in foreign countries	$ 920,006,000

Leases (Details) - USD ($) $ in Thousands	12 Months Ended
Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Operating Leased Assets [Line Items]
Rental expense	$ 43,900	$ 41,600	$ 43,300
Royalty expense	349,000	$ 286,800	$ 230,500
Surety bonds outstanding	263,000
Secured lease obligation outstanding	263,000
Operating Lease [Member]
Operating Leased Assets [Line Items]
2011	28,903
2012	27,610
2013	25,119
2014	17,641
2015	9,648
Thereafter	12,640
Total	121,561
Leases [Member]
Operating Leased Assets [Line Items]
Surety bonds outstanding	64,600
Secured lease obligation outstanding	64,600
Royalty Agreements [Member] \| Royalties [Member]
Operating Leased Assets [Line Items]
2011	24,378
2012	25,595
2013	25,810
2014	27,565
2015	24,397
Thereafter	114,371
Total	$ 242,116

Guarantees (Details) Unit1 in Millions, $ in Millions	12 Months Ended
Guarantees (Details) Unit1 in Millions, $ in Millions	Dec. 31, 2011 USD ($)
Magnum [Member]
Guarantees and Commitments
Guarantee obligations, maximum exposure, undiscounted	$ 15.3
Excess of the current market cost of purchasing coal over the selling price	$ 199.4
Volume of purchased coal in tons	9.8
Performance Guarantee [Member] \| Magnum [Member]
Guarantees and Commitments
Volume of purchased coal in tons	0.7
Bonding Requirements [Member] \| Magnum [Member]
Guarantees and Commitments
Surety bonds posted in the company's favor	$ 48.9
Letters of credit posted in the Company's favor	16.1
Guarantee obligations, maximum exposure, undiscounted	38.5
Indemnification Agreement [Member]
Guarantees and Commitments
Guarantee obligations, maximum exposure, undiscounted	19.3
Coal, materials and supplies and capital commitments, other than reserve acquisitions, and transportation capacity agreements [Member]
Guarantees and Commitments
Unrecorded Unconditional Purchase Obligation Due Current	487.5
Unrecorded Unconditional Purchase Obligation Due in Two Years	139.2
Unrecorded Unconditional Purchase Obligation Due in Three Years	175.0
Unrecorded Unconditional Purchase Obligation Due in Four Years	163.9
Unrecorded Unconditional Purchase Obligation Due in Five Years	128.3
Unrecorded Unconditional Purchase Obligation, Due after Five Years	$ 154.8

Contingencies (Details) $ in Millions	12 Months Ended
Contingencies (Details) $ in Millions	Dec. 31, 2011 USD ($)
Loss Contingencies [Line Items]
Purchase replacement coal	$ 100.0
Damages and interest awarded	104.1
Appeal bond	124.9
Amount accrued	108.3
Interest recognized post-acquisition	3.4
Minimum [Member]
Loss Contingencies [Line Items]
Aggregate amount of past and future damages	228.0
Maximum [Member]
Loss Contingencies [Line Items]
Aggregate amount of past and future damages	$ 377.0

Quarterly Financial Information (Details) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended								12 Months Ended
	Jun. 30, 2010 USD ($)	Dec. 31, 2011 USD ($) $ / shares	Sep. 30, 2011 USD ($) $ / shares	Jun. 30, 2011 USD ($) $ / shares	Mar. 31, 2011 USD ($) $ / shares	Dec. 31, 2010 USD ($) $ / shares	Sep. 30, 2010 USD ($) $ / shares	Jun. 30, 2010 USD ($) $ / shares	Mar. 31, 2010 USD ($) $ / shares	Dec. 31, 2011 USD ($) $ / shares	Dec. 31, 2010 USD ($) $ / shares	Dec. 31, 2009 USD ($) $ / shares	Oct. 01, 2009
Quarterly Financial Information [Line Items]
Revenues		$ 1,228,756	$ 1,198,673	$ 985,528	$ 872,938	$ 835,394	$ 874,705	$ 764,295	$ 711,874	$ 4,285,895	$ 3,186,268	$ 2,576,081
Gross profit		153,280	118,974	171,440	129,773	107,514	119,957	100,461	61,852
Income (loss) from operations		139,728	76,256	95,354	102,238	86,938	98,347	106,499	32,200	413,576	323,984	123,714
Net income		$ 71,215	$ 9,121	$ 6,630	$ 55,874	$ 48,031	$ 46,859	$ 66,274	$ (1,770)	$ 142,840	$ 159,394	$ 42,179
Basic earnings (loss) per common share \| $ / shares		$ 0.34	$ 0.04	$ 0.04	$ 0.34	$ 0.29	$ 0.29	$ 0.41	$ (0.01)	$ 0.75	$ 0.98	$ 0.28
Diluted earnings (loss) per common share \| $ / shares		$ 0.33	$ 0.04	$ 0.04	$ 0.34	$ 0.29	$ 0.29	$ 0.41	$ (0.01)	$ 0.74	$ 0.97	$ 0.28
Gain on Knight Hawk transaction								$ 41,600			$ 41,577
Acquisition and transition costs										$ 54,676
Quarterly Financial Information, Quarterly Charges and Credits, Amount Reconciling to Previously Reported Results			$ 10,200	$ 4,800
Effective tax rate (in hundredths)			37.00%	37.00%
Parent/Issuer [Member]
Quarterly Financial Information [Line Items]
Income (loss) from operations										424,679	309,586	$ 103,535
Net income										$ 142,840	$ 159,394	$ 42,179
Jacobs Ranch Mining Operations [Member]
Quarterly Financial Information [Line Items]
Tons Of Coal													345,000,000
ICG [Member]
Quarterly Financial Information [Line Items]
Expensed costs related to acquisition				$ 98,200
Acquisition and transition costs		$ 1,300	$ 4,700
Knight Hawk [Member]
Quarterly Financial Information [Line Items]
Additional ownership interest	9.00%							9.00%
Gain on Knight Hawk transaction	$ 41,600
Reserves [Member] \| Knight Hawk [Member]
Quarterly Financial Information [Line Items]
Tons Of Coal	68,400,000							68,400,000