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Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2016	Feb. 16, 2017	Jun. 30, 2016
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, 2016
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	FY
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		25,001,819
Entity Well known seasoned issuer	Yes
Entity Voluntary Filers	No
Entity Current reporting status	Yes
Entity Public Float			$ 6.4

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2016	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
Predecessor [Member]
Revenues		$ 1,398,709	$ 2,573,260	$ 2,937,119
Costs, expenses and other operating
Cost of sales (exclusive of items shown separately below)		1,264,464	2,172,753	2,533,284
Depreciation, depletion and amortization		191,581	379,345	418,748
Accretion on asset retirement obligations		24,321	33,680	32,909
Amortization of sales contracts, net		(728)	(8,811)	(13,187)
Change in fair value of coal derivatives and coal trading activities, net		2,856	(1,583)	(3,686)
Asset impairment and mine closure costs		129,267	2,628,303	24,113
Losses from disposed operations resulting from Patriot Coal bankruptcy		0	116,343	0
Selling, general and administrative expenses		59,343	98,783	114,223
Other operating expense (income), net		(15,257)	19,510	(19,754)
Total operating expenses		1,655,847	5,438,323	3,086,650
Income (loss) from operations		(257,138)	(2,865,063)	(149,531)
Interest expense, net
Interest expense		(135,888)	(397,979)	(390,946)
Interest and investment income		2,653	4,430	7,758
Interest expense, net		(133,235)	(393,549)	(383,188)
Income (loss) before nonoperating expenses		(390,373)	(3,258,612)	(532,719)
Nonoperating expense
Net loss resulting from early retirement of debt and debt restructuring		(2,213)	(27,910)	0
Reorganization income (loss), net		1,630,041	0	0
Nonoperating Income (Expense)		1,627,828	(27,910)	0
Income (loss) before income taxes		1,237,455	(3,286,522)	(532,719)
Provision for (benefit from) income taxes		(4,626)	(373,380)	25,634
Net income (loss)		$ 1,242,081	$ (2,913,142)	$ (558,353)
Earnings per common share
Basic earnings per common share (in dollars per share)		$ 58.33	$ (136.86)	$ (26.31)
Diluted earnings per common share (in dollars per share)		$ 58.28	$ (136.86)	$ (26.31)
Weighted average shares outstanding
Basic weighted average shares outstanding		21,293	21,285	21,222
Diluted weighted average shares outstanding		21,313	21,285	21,222
Successor [Member]
Revenues	$ 575,688
Costs, expenses and other operating
Cost of sales (exclusive of items shown separately below)	470,644
Depreciation, depletion and amortization	32,604
Accretion on asset retirement obligations	7,634
Amortization of sales contracts, net	796
Change in fair value of coal derivatives and coal trading activities, net	396
Asset impairment and mine closure costs	0
Losses from disposed operations resulting from Patriot Coal bankruptcy	0
Selling, general and administrative expenses	22,836
Other operating expense (income), net	(5,340)
Total operating expenses	529,570
Income (loss) from operations	46,118
Interest expense, net
Interest expense	(11,241)
Interest and investment income	487
Interest expense, net	(10,754)
Income (loss) before nonoperating expenses	35,364
Nonoperating expense
Net loss resulting from early retirement of debt and debt restructuring	0
Reorganization income (loss), net	(759)
Nonoperating Income (Expense)	(759)
Income (loss) before income taxes	34,605
Provision for (benefit from) income taxes	1,156
Net income (loss)	$ 33,449
Earnings per common share
Basic earnings per common share (in dollars per share)	$ 1.34
Diluted earnings per common share (in dollars per share)	$ 1.31
Weighted average shares outstanding
Basic weighted average shares outstanding	25,002
Diluted weighted average shares outstanding	25,469

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2016	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
Predecessor [Member]
Net income (loss)		$ 1,242,081	$ (2,913,142)	$ (558,353)
Derivative instruments
Comprehensive income (loss) before tax		(532)	(3,477)	3,102
Income tax benefit (provision)		80	1,252	(1,117)
Derivatives Qualifying as Hedges, Adjustment, Net of Tax		(452)	(2,225)	1,985
Pension, postretirement and other post-employment benefits
Comprehensive income (loss) before tax		(1,848)	(5,592)	(44,143)
Income tax benefit (provision)		483	2,011	15,891
Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax		(1,365)	(3,581)	(28,252)
Available-for-sale securities
Comprehensive income (loss) before tax		2,968	1,185	(12,788)
Income tax benefit (provision)		(1,042)	(435)	4,604
Available-for-sale Securities Adjustment, Net of Tax		1,926	750	(8,184)
Total other comprehensive income (loss)		109	(5,056)	(34,451)
Total comprehensive income (loss)		$ 1,242,190	$ (2,918,198)	$ (592,804)
Successor [Member]
Net income (loss)	$ 33,449
Derivative instruments
Comprehensive income (loss) before tax	0
Income tax benefit (provision)	0
Derivatives Qualifying as Hedges, Adjustment, Net of Tax	0
Pension, postretirement and other post-employment benefits
Comprehensive income (loss) before tax	24,067
Income tax benefit (provision)	0
Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	24,067
Available-for-sale securities
Comprehensive income (loss) before tax	387
Income tax benefit (provision)	0
Available-for-sale Securities Adjustment, Net of Tax	387
Total other comprehensive income (loss)	24,454
Total comprehensive income (loss)	$ 57,903

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current assets
Other current assets		$ 39,866
Current liabilities
Current maturities of debt		5,042,353
Predecessor [Member]
Current assets
Cash and cash equivalents		450,781
Short term investments		200,192
Restricted cash		97,542
Trade accounts receivable (net of allowance for doubtful accounts of $0.0 million and $7.8 million, respectively)		117,405
Other receivables		18,362
Inventories		196,720
Prepaid royalties		10,022
Deferred income taxes		0
Coal derivative assets		8,035
Other current assets		39,866
Total current assets		1,138,925
Property, plant and equipment
Coal lands and mineral rights		3,713,639
Plant and equipment		2,359,674
Deferred mine development		553,286
Property, plant and equipment, gross		6,626,599
Less accumulated depreciation, depletion and amortization		(3,007,570)
Property, plant and equipment, net		3,619,029
Other assets
Prepaid royalties		23,671
Equity investments		201,877
Other noncurrent assets		58,379
Total other assets		283,927
Total assets		5,041,881
Current liabilities
Accounts payable		128,131
Accrued expenses and other current liabilities		329,450
Current maturities of debt		5,042,353
Total current liabilities		5,499,934
Long-term debt		30,953
Asset retirement obligations		396,659
Accrued pension benefits		27,373
Accrued postretirement benefits other than pension		99,810
Accrued workers’ compensation		112,270
Other noncurrent liabilities		119,171
Total liabilities		6,286,170
Stockholders' equity (deficit)
Common stock		2,145
Paid-in capital		3,054,211
Treasury stock, at cost		(53,863)
Retained earnings (accumulated deficit)		(4,244,967)
Accumulated other comprehensive income (loss)		(1,815)
Total stockholders’ equity (deficit)		(1,244,289)
Total liabilities and stockholders’ equity (deficit)		$ 5,041,881
Successor [Member]
Current assets
Cash and cash equivalents	$ 305,372
Short term investments	88,072
Restricted cash	71,050
Trade accounts receivable (net of allowance for doubtful accounts of $0.0 million and $7.8 million, respectively)	184,483
Other receivables	19,877
Inventories	113,462
Prepaid royalties	2,281
Deferred income taxes	0
Coal derivative assets	262
Other current assets	93,763
Total current assets	878,622
Property, plant and equipment
Coal lands and mineral rights	387,591
Plant and equipment	418,182
Deferred mine development	280,323
Property, plant and equipment, gross	1,086,096
Less accumulated depreciation, depletion and amortization	(32,493)
Property, plant and equipment, net	1,053,603
Other assets
Prepaid royalties	0
Equity investments	96,074
Other noncurrent assets	108,298
Total other assets	204,372
Total assets	2,136,597
Current liabilities
Accounts payable	95,953
Accrued expenses and other current liabilities	205,240
Current maturities of debt	11,038
Total current liabilities	312,231
Long-term debt	351,841
Asset retirement obligations	337,227
Accrued pension benefits	38,884
Accrued postretirement benefits other than pension	101,445
Accrued workers’ compensation	184,568
Other noncurrent liabilities	63,824
Total liabilities	1,390,020
Stockholders' equity (deficit)
Common stock	250
Paid-in capital	688,424
Treasury stock, at cost	0
Retained earnings (accumulated deficit)	33,449
Accumulated other comprehensive income (loss)	24,454
Total stockholders’ equity (deficit)	746,577
Total liabilities and stockholders’ equity (deficit)	$ 2,136,597

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Successor [Member]
Allowance for doubtful accounts	$ 0.0
Common stock, par value (in dollars per share)	$ 0.01
Common stock, shares authorized	300,000,000
Common stock, shares issued	25,002,000
Predecessor [Member]
Allowance for doubtful accounts		$ 7.8
Common stock, par value (in dollars per share)		$ 0.01
Common stock, shares authorized		26,000,000
Common stock, shares issued		21,446,000

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2016	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
Predecessor [Member]
Operating activties
Net income (loss)		$ 1,242,081	$ (2,913,142)	$ (558,353)
Adjustments to reconcile net income (loss) to cash provided by (used in) operating activities:
Depreciation, depletion and amortization		191,581	379,345	418,748
Accretion on asset retirement obligations		24,321	33,680	32,909
Amortization of sales contracts, net		(728)	(8,811)	(13,187)
Prepaid royalties expensed		4,791	8,109	9,698
Deferred income taxes		(419)	(367,210)	25,152
Employee stock-based compensation expense		2,096	5,760	9,847
Gains on disposals and divestitures		(6,628)	(2,270)	(27,512)
Asset impairment and noncash mine closure costs		119,194	2,613,345	16,868
Losses from disposed operations resulting from Patriot Coal bankruptcy		0	116,343	0
Amortization relating to financing activities		12,800	25,241	17,363
Net loss resulting from early retirement of debt and debt restructuring		2,213	27,910	0
Non-cash bankruptcy reorganization items		(1,775,910)	0	0
Changes in:
Receivables		(42,786)	98,212	(8,991)
Inventories		34,440	(6,534)	41,548
Coal derivative assets and liabilities		5,678	973	5,449
Accounts payable, accrued expenses and other current liabilities		15,316	(15,532)	41,680
Asset retirement obligations		(12,041)	(17,040)	(14,621)
Pension, postretirement and other postemployment benefits		(15,692)	4,800	(25,347)
Other		(28,525)	(27,546)	(4,833)
Cash provided by (used in) operating activities		(228,218)	(44,367)	(33,582)
Investing activities
Capital expenditures		(82,434)	(119,024)	(147,286)
Minimum royalty payments		(305)	(5,871)	(7,317)
Proceeds from disposals and divestitures		(2,921)	2,191	62,358
Purchases of short term investments		(98,750)	(246,735)	(211,929)
Proceeds from sales of short term investments		185,859	290,205	205,611
Proceeds from sale of investments in equity investments and securities		1,147	2,259	9,464
Investments in and advances to affiliates, net		(3,441)	(11,502)	(16,657)
Withdrawals (deposits) of restricted cash		15,979	(91,864)	(5,678)
Cash provided by (used in) investing activities		15,134	(180,341)	(111,434)
Financing activities
Payments to retire debt		0	0	(300)
Payments on term loan		0	(19,500)	(19,500)
Net receipts (payments) on other debt		(11,986)	(11,332)	(5,395)
Debt financing costs		(23,011)	0	(4,519)
Dividends paid		0	0	(2,123)
Expenses related to debt restructuring		(2,213)	(27,910)	0
Other		0	0	(15)
Cash provided by (used in) financing activities		(37,210)	(58,742)	(31,852)
Increase (decrease) in cash and cash equivalents		(250,294)	(283,450)	(176,868)
Cash and cash equivalents, beginning of period	$ 200,487	450,781	734,231	911,099
Cash and cash equivalents, end of period		200,487	450,781	734,231
SUPPLEMENTAL CASH FLOW INFORMATION
Cash paid during the period for interest		79,979	283,337	361,727
Cash refunded during the period for income taxes, net		49	$ 4,138	$ 4,896
Successor [Member]
Operating activties
Net income (loss)	33,449
Adjustments to reconcile net income (loss) to cash provided by (used in) operating activities:
Depreciation, depletion and amortization	32,604
Accretion on asset retirement obligations	7,634
Amortization of sales contracts, net	796
Prepaid royalties expensed	2,587
Deferred income taxes	3
Employee stock-based compensation expense	1,032
Gains on disposals and divestitures	(485)
Asset impairment and noncash mine closure costs	0
Losses from disposed operations resulting from Patriot Coal bankruptcy	0
Amortization relating to financing activities	467
Net loss resulting from early retirement of debt and debt restructuring	0
Non-cash bankruptcy reorganization items	0
Changes in:
Receivables	(22,196)
Inventories	24,870
Coal derivative assets and liabilities	1,662
Accounts payable, accrued expenses and other current liabilities	34,129
Asset retirement obligations	(4,535)
Pension, postretirement and other postemployment benefits	(5,625)
Other	(22,200)
Cash provided by (used in) operating activities	84,192
Investing activities
Capital expenditures	(15,214)
Minimum royalty payments	(63)
Proceeds from disposals and divestitures	572
Purchases of short term investments	0
Proceeds from sales of short term investments	23,000
Proceeds from sale of investments in equity investments and securities	0
Investments in and advances to affiliates, net	(823)
Withdrawals (deposits) of restricted cash	10,512
Cash provided by (used in) investing activities	17,984
Financing activities
Payments to retire debt	0
Payments on term loan	(816)
Net receipts (payments) on other debt	3,374
Debt financing costs	0
Dividends paid	0
Expenses related to debt restructuring	0
Other	151
Cash provided by (used in) financing activities	2,709
Increase (decrease) in cash and cash equivalents	104,885
Cash and cash equivalents, beginning of period	200,487
Cash and cash equivalents, end of period	305,372	$ 200,487
SUPPLEMENTAL CASH FLOW INFORMATION
Cash paid during the period for interest	39,620
Cash refunded during the period for income taxes, net	$ 287

Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock [Member]	Paid-in Capital [Member]	Treasury Stock, at Cost [Member]	Retained Earnings (Accumulated Deficit) [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning Balance (Predecessor [Member]) at Dec. 31, 2013	$ 2,253,249	$ 2,141	$ 3,038,613	$ (53,848)	$ (771,349)	$ 37,692
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income (loss) \| Predecessor [Member]	(592,804)				(558,353)	(34,451)
Employee stock-based compensation expense \| Predecessor [Member]	9,847		9,847
Dividends on common shares ($0.01 per share) \| Predecessor [Member]	(2,123)				(2,123)
Treasury shares purchased \| Predecessor [Member]	(15)			(15)
Ending Balance (Predecessor [Member]) at Dec. 31, 2014	1,668,154	2,141	3,048,460	(53,863)	(1,331,825)	3,241
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income (loss) \| Predecessor [Member]	(2,918,198)				(2,913,142)	(5,056)
Issuance of 64 shares of common stock under the stock incentive plan-restricted stock and restricted stock units, net of forfeitures \| Predecessor [Member]	(5)	4	(9)
Employee stock-based compensation expense \| Predecessor [Member]	5,760		5,760
Ending Balance (Predecessor [Member]) at Dec. 31, 2015	(1,244,289)	2,145	3,054,211	(53,863)	(4,244,967)	(1,815)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income (loss) \| Predecessor [Member]	1,242,190				1,242,081	109
Employee stock-based compensation expense \| Predecessor [Member]	2,099		2,099
Elimination of predecessor equity \| Predecessor [Member]	0	(2,145)	(3,056,310)	53,863	3,002,886	1,706
Ending Balance (Predecessor [Member]) at Oct. 01, 2016	0	0	0	0	0	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of successor equity \| Successor [Member]	687,483	250	687,233
Warrants exercised \| Successor [Member]	159		159
Total comprehensive income (loss) \| Successor [Member]	57,903				33,449	24,454
Employee stock-based compensation expense \| Successor [Member]	1,032		1,032
Ending Balance (Successor [Member]) at Dec. 31, 2016	$ 746,577	$ 250	$ 688,424	$ 0	$ 33,449	$ 24,454

Consolidated Statements of Stockholders' Equity (Deficit) (Parenthetical) - Predecessor [Member] - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Restricted stock shares issued, net	64
Dividends declared per common share (in dollars per share)		$ 0.01

Basis of Presentation	12 Months Ended
Basis of Presentation	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements include the accounts of Arch Coal, Inc. and its subsidiaries and controlled entities (the “Company”). Unless the context indicates otherwise, the terms “Arch” and the “Company” are used interchangeably in this Annual Report on Form 10-K refer to both the Predecessor and Successor Company. The Company’s primary business is the production of thermal and metallurgical coal from surface and underground mines located throughout the United States, for sale to utility, industrial and steel producers both in the United States and around the world. The Company currently operates mining complexes in West Virginia, Kentucky, Virginia, Illinois, Wyoming and Colorado. All subsidiaries are wholly-owned. Intercompany transactions and accounts have been eliminated in consolidation. Chapter 11 Filing and Emergence from Bankruptcy On January 11, 2016 (the “Petition Date”), Arch and substantially all of its wholly owned domestic subsidiaries (the “Filing Subsidiaries” and, together with Arch, the “Debtors”) filed voluntary petitions for reorganization (collectively, the “Bankruptcy Petitions”) under Chapter 11 of Title 11 of the U.S. Code (the “Bankruptcy Code”) in the United States Bankruptcy Court for the Eastern District of Missouri (the “Court”). The Debtor’s Chapter 11 Cases (collectively, the “Chapter 11 Cases”) were jointly administered under the caption In re Arch Coal, Inc., et al. Case No. 16-40120 (lead case). During the bankruptcy proceedings, each Debtor operated its business as a “debtor in possession” under the jurisdiction of the Court and in accordance with the applicable provisions of the Bankruptcy Code and the orders of the Court. For periods subsequent to filing the Bankruptcy Petitions, the Company applied the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 852, “Reorganizations”, in preparing its consolidated financial statements. ASC 852 requires that financial statements distinguish transactions and events that are directly associated with the reorganization from the ongoing operations of the business. Accordingly, certain revenues, expenses, realized gains and losses and provisions for losses that are realized or incurred in the bankruptcy proceedings have been recorded in a reorganization line item on the Consolidated Statement of Operations. In addition, the pre-petition obligations that may be impacted by the bankruptcy reorganization process were classified on the balance sheet as liabilities subject to compromise. On September 13, 2016, the Bankruptcy Court entered an order, Docket No. 1324, confirming the Debtors’ Fourth Amended Joint Plan of Reorganization under Chapter 11 of the Bankruptcy Code dated as of September 11, 2016 (the “Plan”), which order was amended on September 15, 2016, Docket No. 1334. On October 5, 2016, Arch Coal satisfied the closing conditions contemplated by the Plan, which became effective on that date (the “Effective Date”). On the Plan Effective Date, the Company applied fresh start accounting which requires the Company to allocate its reorganization value to the fair value of assets and liabilities in conformity with the guidance for the acquisition method of accounting for business combinations. In addition to fresh start accounting, the Company’s consolidated financial statements reflect all impacts of the transactions contemplated by the Plan. Under the provisions of fresh start accounting, a new entity has been created for financial reporting purposes. The Company selected an accounting convenience date of October 1, 2016 for purposes of applying fresh start accounting as the activity between the convenience date and the Effective Date does not result in a material difference in the results. References to “Successor” in the financial statements and accompanying footnotes are in reference to reporting dates on or after October 2, 2016; references to “Predecessor” in the financial statements and accompanying footnotes are in reference to reporting dates through October 1, 2016 which includes the impact of the Plan provisions and the application of fresh start accounting. As such, the Company’s financial statements for the Successor will not be comparable in many respects to its financial statements for periods prior to the adoption of fresh start accounting and prior to the accounting for the effects of the Plan. For further information on fresh start accounting, please see Note 3 to the Consolidated Financial Statements, “Emergence from Bankruptcy and Fresh Start Accounting.”

Accounting Policies

12 Months Ended

Dec. 31, 2016

Accounting Policies [Abstract]

Accounting Policies

The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States for financial reporting and U.S. Securities and Exchange Commission regulations.

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.

Restricted cash

Restricted cash represents cash collateral supporting letters of credit issued under the Company’s accounts receivable securitization program.

Accounts Receivable

Accounts receivable are recorded at amounts that are expected to be collected, based on past collection history, the economic environment and specified risks identified in the receivables portfolio.

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 or loss is reflected in “Other operating expense (income), net” in the consolidated statements of operations. Information about investment activity is provided in Note 9 to the Consolidated Financial Statements, “Equity Method Investments and Membership Interests in Joint Ventures.”

Investments in debt securities and marketable equity securities that do not qualify for equity method accounting are classified as available-for-sale and are recorded at their fair values. Unrealized gains and losses on these investments are recorded in other comprehensive income or loss. A decline in the value of an investment that is considered other-than-temporary would be recognized in operating expenses.

Sales Contracts

Coal supply agreements (sales contracts) valued during fresh start accounting or 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 10 to the Consolidated Financial Statements, “Sales Contracts” for further information related to the Company’s 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.

Prepaid Royalties

Leased mineral rights are often acquired through royalty payments. When royalty payments represent prepayments recoupable against royalties owed on future revenues from the underlying coal, they are recorded as a prepaid asset, with amounts expected to be recouped within one year classified as current. When coal from these leases is sold, the royalties owed are recouped against the prepayment and charged to cost of sales. An impairment charge is recognized for prepaid royalties that are not expected to be recouped.

Property, Plant and Equipment

Plant and Equipment

Plant and equipment were fair valued at emergence during fresh start accounting; subsequent purchases of property, plant and equipment have been recorded at cost. Interest costs incurred during the construction period for major asset additions are capitalized. The Company did not capitalize any interest costs during the periods October 2 through December 31, 2016, January 1 through October 1, 2016 or for the year ended December 31, 2015, respectively. 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 is 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 7 to 18 years. The useful lives of buildings and leasehold improvements generally range from 1 to 18 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. 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.

The net book value of the Company’s coal interests was $0.4 billion and $2.4 billion at December 31, 2016 and 2015, respectively. 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.

The Company currently does not have any future lease bonus payments.

Depreciation, depletion and amortization

The depreciation, depletion and amortization related to long-lived assets is reflected in the statement of operations as a separate line item. No depreciation, depletion or amortization is included in any other operating cost categories.

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. See additional discussion in Note 5 to the Consolidated Financial Statements, “Impairment Charges and Mine Closure 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. Debt issuance costs related to a recognized liability are presented in the balance sheet as a direct reduction from the carrying amount of that liability whereas debt issuance costs related to a credit facility with no balance outstanding are shown as an asset. The unamortized balance of deferred financing costs was $5.2 million at December 31, 2016, with $1.9 million classified as current. As these amounts relate to a credit facility with no outstanding borrowings, these current amounts are classified within “Other current assets” and the noncurrent amounts are classified within “Other noncurrent assets.” The unamortized balance of deferred financing costs at December 31, 2015 was $66.3 million with $65.6 million classified as current. As these debt issuance costs primarily related to a recognized liability, the current amounts are recorded in “Current maturities of debt” and the noncurrent amounts are recorded in “Long-term debt” 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 Expense (Income), net

Other operating expense (income), net in the accompanying consolidated statements of operations reflects income and expense from sources other than physical coal sales, including: bookouts, or the practice of offsetting purchase and sale contracts for shipping convenience purposes; contract settlements; liquidated damage charges related to unused terminal and port capacity; royalties earned from properties leased to third parties; income from equity investments (Note 9); gains and losses from divestitures and dispositions of assets; and realized gains and losses on derivatives that do not qualify for hedge accounting and are not held for trading purposes (Note 11).

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 discounted cash flow 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 15, “Asset Retirement Obligations.”

Loss Contingencies

The Company accrues for cost related to contingencies when a loss is probable and the amount is reasonably determinable. Disclosure of contingencies is included in the financial statements when it is at least reasonably possible that a material loss or an additional material loss in excess of amounts already accrued may be incurred. The amount accrued represents the Company’s best estimate of the loss, or, if no best estimate within a range of outcomes exists, the minimum amount in the range.

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 or loss. Amounts in other comprehensive income or loss 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 periods disclosed within.

See Note 11, “Derivatives” 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 16, “Fair Value Measurements” for further disclosures related to the Company’s recurring fair value estimates.

Income Taxes

Deferred income taxes are provided for temporary differences arising from differences between the financial statement 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. 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 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 the reversal of temporary differences.

Benefits from tax positions that are uncertain are not recognized unless the Company concludes that it is more likely than not that the position would be sustained in a dispute with taxing authorities, should the dispute be taken to the court of last resort. The Company would measure any such benefit at the largest amount of benefit that is greater than 50 percent likely of being realized upon settlement with taxing authorities.

See Note 14, “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. On January 1, 2015 the Company’s cash balance and excess pension plans were amended to freeze new service credits for any new or active employee. 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. The Company amortizes actuarial gains and losses over the remaining service attribution periods of the employees using the corridor method. See Note 20, “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 over the requisite service period. The grant-date fair value of option awards and restricted stock awards with a market condition is determined using a Monte Carlo simulation. 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.”

Recently Adopted Accounting Guidance

In April 2015, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2015-03 (“ASU 2015-03”), Simplifying the Presentation of Debt Issuance Costs. ASU 2015-03 required debt issuance costs related to a recognized liability to be presented in the balance sheet as a direct reduction from the carrying amount of that liability, consistent with debt discounts. The Company adopted ASU 2015-03 in the first quarter of 2016 as mandated by the standard. The following reflects the retrospective application:



	December 31, 2015
	(in thousands)
Other current assets, prior to revision	$	104,723
Revision of debt issuance costs	(64,857		)

Other current assets, as revised	$	39,866

Current maturities of debt, prior to revision	$	5,107,210
Revision of debt issuance costs	(64,857		)

Current maturities of debt, as revised	$	5,042,353

Effective December 31, 2016, the Company adopted ASU No. 2014-15 (“ASU 2014-15”), Disclosures of Uncertainties about an Entity’s Ability to Continue as a Going Concern. ASU 2014-15 requires management to evaluate for each annual and interim reporting period whether conditions or events give rise to substantial doubt that an entity has the ability to continue as a going concern within one year following issuance of the financial statements and requires specific disclosures regarding the conditions or events leading to substantial doubt. The adoption of ASU 2014-15 did not have any impact on the Company’s financial position or results of operations.

Effective December 31, 2016, the Company adopted the Accounting Standards Update No. 2015-17 (“ASU 2015-17”), Balance Sheet Classification of Deferred Taxes which requires that all deferred tax assets and liabilities, along with any related valuation allowance be classified as noncurrent on the balance sheet. The standard has been applied on a retrospective basis. The adoption of ASU 2015-17 did not have any impact on the Company’s financial position or results of operations.

Investments at fair value include investments in funds, including certain money market funds, that are measured at net asset value (“NAV”). The Company uses NAV to measure the fair value of its fund investments when (i) the fund investment does not have a readily determinable fair value and (ii) the NAV of the investment fund is calculated in a manner consistent with the measurement principles of investment company accounting, including measurement of the underlying investments at fair value. The Company adopted ASU No. 2015-07 in January 2016, and, as required, disclosures in the paragraphs and tables below are limited to only those investments in funds that are measured at NAV. In accordance with ASU No. 2015-07, previously reported amounts have been conformed to the current presentation.

Recent Accounting Guidance Issued Not Yet Effective

In May 2014, the FASB issued ASU No. 2014-09, “Revenue from Contracts with Customers.” ASU 2014-09 is a comprehensive revenue recognition standard that will supersede nearly all existing revenue recognition guidance under current U.S. GAAP and replace it with a principle based approach for determining revenue recognition. ASU 2014-09 will require that companies recognize revenue based on the value of transferred goods or services as they occur in the contract. The ASU also will require additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments and assets recognized from costs incurred to obtain or fulfill a contract. ASU 2014-09 is effective for interim and annual periods beginning after December 15, 2017. Early adoption is permitted only in annual reporting periods beginning after December 15, 2016, including interim periods therein. Entities will be able to transition to the standard either retrospectively or as a cumulative-effect adjustment as of the date of adoption. The Company’s primary source of revenue is from the sale of coal through both short-term and long-term contracts with utilities, industrial customers and steel producers whereby revenue is currently recognized when risk of loss has passed to the customer. Upon adoption of this new standard, the Company believes that the timing of revenue recognition related to our coal sales will remain consistent with our current practice. The Company is currently evaluating other revenue streams to determine the potential impact related to the adoption of the standard, as well as potential disclosures required by the standard. The Company will be adopting the standard under the modified retrospective approach.

In February 2016, the FASB issued ASU No. 2016-02, “Leases” which, for operating leases, requires a lessee to recognize a right-of-use asset and a lease liability, initially measured at the present value of the lease payments, in its balance sheet. The standard also requires a lessee to recognize a single lease cost, calculated so that the cost of the lease is allocated over the term of the lease, on a generally straight line basis. The ASU is effective for public companies for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years; early adoption is permitted. The Company has both operating and capital leases. We expect the adoption of this standard to result in the recognition of right-of-use assets and lease liabilities not currently recorded on the Company’s financial statements. The Company is currently in the process of accumulating all contractual lease arrangements in order to determine the impact on its financial statements.

In October 2016, the FASB issued ASU No. 2016-18, “Statement of Cash Flows-Restricted Cash.” The amendment requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. Therefore, amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning period and end of period total amounts shown on the statement of cash flows. ASU 2016-18 is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years; early adoption is permitted.

Emergence from Bankruptcy and Fresh Start Accounting

12 Months Ended

Dec. 31, 2016

Reorganizations [Abstract]

Emergence from Bankruptcy and Fresh Start Accounting

On January 11, 2016 (the “Petition Date”), Arch and substantially all of its wholly owned domestic subsidiaries (the “Filing Subsidiaries” and, together with Arch, the “Debtors”) filed voluntary petitions for reorganization (collectively, the “Bankruptcy Petitions”) under Chapter 11 of Title 11 of the U.S. Code (the “Bankruptcy Code”) in the United States Bankruptcy Court for the Eastern District of Missouri (the “Court”). The Debtor’s Chapter 11 Cases (collectively, the “Chapter 11 Cases”) were jointly administered under the caption In re Arch Coal, Inc., et al. Case No. 16-40120 (lead case). During the bankruptcy proceedings, each Debtor operated its business as a “debtor in possession” under the jurisdiction of the Court and in accordance with the applicable provisions of the Bankruptcy Code and the orders of the Court.

For periods subsequent to filing the Bankruptcy Petitions, the Company applied the FASB Accounting Standards Codification (“ASC”) 852, “Reorganizations”, in preparing its consolidated financial statements. ASC 852 requires that financial statements distinguish transactions and events that are directly associated with the reorganization from the ongoing operations of the business. Accordingly, certain revenues, expenses, realized gains and losses and provisions for losses that are realized or incurred in the bankruptcy proceedings have been recorded in a reorganization line item on the Consolidated Statement of Operations. In addition, the pre-petition obligations that may be impacted by the bankruptcy reorganization process were classified on the balance sheet as liabilities subject to compromise.

On September 13, 2016, the Bankruptcy Court entered an order, Docket No. 1324, confirming the Debtors’ Fourth Amended Joint Plan of Reorganization under Chapter 11 of the Bankruptcy Code dated as of September 11, 2016 (the “Plan”), which order was amended on September 15, 2016, Docket No. 1334.

On October 5, 2016, Arch Coal satisfied the closing conditions contemplated by the Plan, which became effective on that date (the “Effective Date”).

On the Plan Effective Date, the Company applied fresh start accounting which requires the Company to allocate its reorganization value to the fair value of assets and liabilities in conformity with the guidance for the acquisition method of accounting for business combinations. In addition to fresh start accounting, the Company’s consolidated financial statements reflect all impacts of the transactions contemplated by the Plan. Under the provisions of fresh start accounting, a new entity has been created for financial reporting purposes. The Company selected an accounting convenience date of October 1, 2016 for purposes of applying fresh start accounting as the activity between the convenience date and the Effective Date does not result in a material difference in the results. References to “Successor” in the financial statements and accompanying footnotes are in reference to reporting dates on or after October 2, 2016; references to “Predecessor” in the financial statements and accompanying footnotes are in reference to reporting dates through October 1, 2016 which includes the impact of the Plan provisions and the application of fresh start accounting. As such, the Company’s financial statements for the Successor will not be comparable in many respects to its financial statements for periods prior to the adoption of fresh start accounting and prior to the accounting for the effects of the Plan.

The following is a summary of certain provisions of the Plan, as confirmed by the Bankruptcy Court pursuant to the Confirmation Order, and is not intended to be a complete description of the Plan.

Treatment of Claims

The Plan contemplates that:


•	Holders of allowed administrative expense claims, priority claims (other than administrative expense claims and priority tax claims) and secured claims (other than claims arising under priority claims, the prepetition first lien credit facility and prepetition second lien notes) will be paid in full.

•

Holders of allowed claims arising under the Debtors’ prepetition first lien credit facility (“First Lien Credit Facility”) will receive their pro rata distribution of (i) total cash payments equal to the greater of (A) $144.8 million less the amount of the adequate protection payments and (B) $30 million; (ii) $326.5 million in principal amount of New First Lien Debt Facility; and (iii) 94% of the common stock of Reorganized Arch Coal (the “New Common Stock”), subject to dilution on account of (a) any Class A Common Stock (as defined below) issued upon exercise of the warrants (the “New Warrants”) issued pursuant to the Plan to purchase up to 12% of the fully diluted Class A Common Stock as of the Effective Date and exercisable at any time for a period of 7 years from the Effective Date at a strike price calculated based on a total equity capitalization of $1.425 billion ($57 per share) and (b) the issuance of New Common Stock in an amount of up to 10% of the New Common Stock, on a fully diluted basis, pursuant to a management incentive plan (the “Management Incentive Plan”).

•

Holders of allowed claims on account of prepetition second lien or unsecured notes (the “Prepetition Notes”) will receive their pro rata distribution of (i) $22.636 million in cash, (ii) at such holder’s election, either (A) such holder’s pro rata share of the New Warrants or (B) such holder’s pro rata share of $25 million in cash and (iii) 6% of the New Common Stock (subject to dilution on account of any exercise of the New Warrants and pursuant to the Management Incentive Plan).


•	Holders of allowed general unsecured claims against Debtors (other than claims on account of the First Lien Credit Facility or Prepetition Notes) will receive their pro rata distribution of $7.364 million cash, less fees and expenses incurred by any professionals retained by a claims oversight committee up to $200,000.

•

The Reorganized Debtors will waive and release any claims or causes of action that they have, had, or may have that are based on sections 502(d), 544, 545, 547, 548, 549, 550, 551, 553(b) and 724(a) of the Bankruptcy Code and analogous non-bankruptcy law for all purposes against (i) prepetition trade creditors and (ii) officers, directors, employees or representatives of the Debtors or the Reorganized Debtors and all agents and representatives of all of the foregoing. However, the Reorganized Debtors will retain the right to assert any said claims as defenses or counterclaims in any cause of action brought by any creditor.

New First Lien Debt Facility

For information related to the New First Lien Debt Facility, see Note 13, “Debt and Financing Arrangements.”

Securitization Facility

For information related to the Securitization Facility, see Note 13, “Debt and Financing Arrangements.”

Warrant Agreement

On the Effective Date, the Company entered into a warrant agreement (the “Warrant Agreement”) with American Stock Transfer & Trust Company, LLC as warrant agent and, pursuant to the terms of the Plan, issued warrants (“Warrants”) to purchase up to an aggregate of 1,914,856 shares of Class A Common Stock, par value $0.01 per share, of Arch Coal (the “Class A Common Stock”) to holders of claims arising under the Cancelled Notes (as defined below). Each Warrant expires on October 5, 2023, and is initially exercisable for one share of Class A Common Stock at an initial exercise price of $57.00 per share. The Warrants are exercisable by a holder paying the exercise price in cash or on a cashless basis, at the election of the holder. The Warrants contain anti-dilution adjustments for stock splits, reverse stock splits, stock dividends, dividends and distributions of cash, other securities or other property, spin-offs and tender and exchange offers by Arch Coal or its subsidiaries to purchase Class A Common Stock at above-market prices.

If, in connection with a merger, recapitalization, business combination, transfer to a third party of substantially all of Arch Coal’s consolidated assets or other transaction that results in a change to the Class A Common Stock (each, a “Transaction”), (i) the Transaction is consummated prior to the fifth anniversary of the Effective Date and the Transaction consideration to holders of Class A Common Stock is 90% or more listed common stock or common stock of a company that provides publicly available financial reporting, and holds management calls regarding the same, no less than quarterly (“Reporting Stock”) or (ii) regardless of the consideration, the Transaction is consummated on or after the fifth anniversary of the Effective Date, the Warrants will be assumed by the surviving company and will become exercisable for the consideration that the holders of Class A Common Stock receive in such Transaction; provided that if the consideration such holders receive consists solely of cash, then upon the consummation of such Transaction, Arch Coal will pay for each Warrant an amount of cash equal to the greater of (i) (x) the amount of cash payable with respect to the number of shares of Class A Common Stock underlying the Warrant minus (y) the exercise price per share then in effect multiplied by the number of shares of Class A Common Stock underlying the Warrant and (ii) $0.

If a Transaction is consummated prior to the fifth anniversary of the Effective Date in which the Transaction consideration is less than 90% Reporting Stock, a portion of the Warrants corresponding to the portion of the Transaction consideration that is Reporting Stock will be assumed by the surviving company and will become exercisable for the Reporting Stock consideration that the holders of Class A Common Stock receive in such Transaction, and the portion of the Warrants corresponding to the portion of the Transaction consideration that is not Reporting Stock will, at the option of each holder, (i) be assumed by the surviving company and will become exercisable for the consideration that the holders of Class A Common Stock receive in such Transaction or (ii) be redeemed by Arch Coal for cash in an amount equal to the Black Scholes Payment (as defined in the Warrant Agreement).

Termination of Material Definitive Agreements

On the Effective Date, by operation of the Plan, all outstanding obligations under the following notes issued by Arch Coal and guaranteed by certain subsidiary guarantors, (collectively, the “Cancelled Notes”) were cancelled and the indentures governing such obligations were cancelled except as necessary to (a) enforce the rights, claims and interests of the applicable trustee vis-a-vis any parties other than the Debtors, (b) allow each trustee to receive distributions under the Plan and to distribute them to the holders of the Cancelled Notes in accordance with the terms of the applicable indenture, (c) preserve any rights of the applicable trustee to compensation, reimbursement and indemnification under each of the applicable indentures solely as against any money or property distributable to holders of Cancelled Notes, (iv) permit each of the trustees to enforce any obligation owed to them under the Plan and (v) permit each of the trustees to appear in the Chapter 11 cases or in any proceeding in the Bankruptcy Court or any other court:


•	7.000% Senior Notes due 2019, issued pursuant to an indenture dated as of June 14, 2011, by and among Arch Coal, as issuer, UMB Bank National Association, as trustee, and the guarantors named therein, as amended, supplemented or revised thereafter;


•	7.250% Senior Notes due 2020, issued pursuant to an indenture dated as of August 9, 2010, by and among Arch Coal, as issuer, U.S. Bank National Association, as trustee, and the guarantors named therein, as amended, supplemented or revised thereafter;


•	7.250% Senior Notes due 2021, issued pursuant to an indenture dated as of June 14, 2011, by and among Arch Coal, as issuer, UMB Bank National Association, as trustee, and the guarantors named therein, as amended, supplemented or revised thereafter;


•	9.875% Senior Notes due 2019, issued pursuant to an indenture dated as of November 21, 2012, by and among Arch Coal, as issuer, UMB Bank National Association, as trustee, and the guarantors named therein, as amended, supplemented or revised thereafter; and


•	8.000% Second Lien notes due 2019, issued pursuant to an indenture dated as of December 17, 2013, by and among Arch Coal, as issuer, Wilmington Savings Fund Society, as trustee and collateral agent as successor to UMB Bank National Association, and the guarantors named therein, as amended, supplemented or revised thereafter.

On the Effective Date, by operation of the Plan, all outstanding obligations under the following credit agreement (the “Prepetition Credit Agreement”) entered into by Arch Coal and guaranteed by certain of Arch Coal’s subsidiaries and the related collateral, guaranty and other definitive agreements relating to the Prepetition Credit Agreement were cancelled and the Prepetition Credit Agreement was cancelled except as necessary to (i) enforce the rights, claims and interests of the Prepetition Agent (as defined below) and any predecessor thereof vis-a-vis the Lenders and any parties other than the Debtors, (ii) to allow the Prepetition Agent to receive distributions under the Plan and to distribute them to the lenders under the Prepetition Credit Agreement and (iii) preserve any rights of the Prepetition Agent and any predecessor thereof as against any money or property distributable to holders of claims arising out of the Prepetition Credit Agreement or any related transaction documents, including any priority in respect of payment and the right to exercise any charging lien:

•

Amended and Restated Credit Agreement, dated as of June 14, 2011 (as amended by the First Amendment, dated as of May 16, 2012, the Second Amendment, dated as of November 20, 2012, the Third Amendment, dated as of November 21, 2012 and the Fourth Amendment, dated as of December 17, 2013), among Arch Coal, Inc., as borrower, the lenders from time to time party thereto, Wilmington Trust, National Association, in its capacities as term loan facility administrative agent (as successor to Bank of America, N.A. in such capacity) and collateral agent (as successor to PNC Bank, National Association in such capacity) (in such capacities, the “Prepetition Agent”)

On the Effective Date, all outstanding obligations under the following credit agreement (the “DIP Credit Agreement”) other than contingent and/or unliquidated obligations were paid in cash in full, all commitments under the DIP Credit Agreement and the related transaction documents referred to therein as the “Loan Documents” were terminated, all liens on property of the Debtors arising out of or related to the DIP Facility terminated and the Loan Documents were cancelled except with respect to (a) contingent and and/or unliquidated obligations under the Loan Documents which survive the Effective Date and continue to be governed by the Loan Documents and (b) the relationships among the DIP Agent (as defined below) and the lenders under the DIP Credit Agreement, as applicable, including but not limited to, those provisions relating to the rights of the DIP Agent and the lenders to expense reimbursement, indemnification and other similar amounts, certain reinstatement obligations set forth in the DIP Credit Agreement and any provisions that may survive termination or maturity of the credit facility governed by the DIP Credit Agreement in accordance with the terms thereof:

•

Superpriority Secured Debtor-In-Possession Credit Agreement, dated as of January 21, 2016 (as amended by the Waiver and Consent and Amendment No. 1, dated as of March 4, 2016, Amendment No. 2, dated as of March 28, 2016, Amendment No. 3, dated as of April 26, 2016, Amendment No. 4, dated as of June 10, 2016, Amendment No. 5, dated as of June 23, 2016, Amendment No. 6, dated as of July 20, 2016, and Amendment No. 7, dated as of September 28, 2016) among Arch Coal, Inc., as borrower, certain subsidiaries of Arch Coal, Inc., as guarantors, the lenders from time to time party there and Wilmington Trust, National Association, in its capacity as administrative agent and as collateral agent (in such capacities, the “DIP Agent”).

Equity Securities

Under the Plan, 24,589,834 shares of Class A Common Stock and 410,166 shares of Class B Common Stock, par value $.01 per share, (“Class B Common Stock” and together with Class A Common Stock, “Common Stock”) were distributed to the secured lenders and to certain holders of general unsecured claims under the Plan on the Effective Date. In addition, on the Effective Date, Arch Coal issued Warrants to purchase up to an aggregate of 1,914,856 shares of Class A Common Stock. Arch Coal relied, based on the confirmation order it received from the Bankruptcy Court, on Section 1145(a)(1) of the U.S. Bankruptcy Code to exempt from the registration requirements of the Securities Act of 1933, as amended (i) the offer and sale of Common Stock to the secured lenders and to the general unsecured creditors, (ii) the offer and sale of the Warrants to the holders of claims arising under the Cancelled Notes and (iii) the offer and sale of the Class A Common Stock issuable upon exercise of the Warrants. Section 1145(a)(1) of the Bankruptcy Code exempts the offer and sale of securities under a plan of

reorganization from registration under Section 5 of the Securities Act and state laws if three principal requirements are satisfied:


•	the securities must be offered and sold under a plan of reorganization and must be securities of the debtor, of an affiliate participating in a joint plan of reorganization with the debtor or of a successor to the debtor under the plan of reorganization;


•	the recipients of the securities must hold claims against or interests in the debtor; and


•	the securities must be issued in exchange, or principally in exchange, for the recipient’s claim against or interest in the debtor.

Reorganization Value

Fresh start accounting provides, among other things, for a determination of the value to be assigned to the equity of the emerging company as of a date selected for financial reporting purposes. In conjunction with the bankruptcy proceedings, a third party financial advisor provided an enterprise value of the Company of approximately $650 million to $950 million. The final equity value of $687.5 million was based upon the approximate high end of the enterprise value established by the third party valuation plus excess cash of $64 million less the fair value of debt related to the New First Lien Debt Facility of $326.5 million. The high end of the enterprise value assumed a minimum cash balance at emergence of $250 million.

The enterprise value of the Company was estimated using various valuation methods including: (i) comparable public company analysis, (ii) discounted cash flow analysis (“DCF”) and (iii) sum-of-the-parts analysis. The comparable public company analysis is based on the enterprise value of selected publicly traded companies that have operating and financial characteristics comparable in certain respects to the Company, for example, operational requirements and risk and profitability characteristics. Selected companies are comprised of coal mining companies with primary operations in the United States. Under this methodology, certain financial multiples and ratios that measure financial performance and value are calculated for each selected company and then applied to the Company’s financials to imply an enterprise value for the Company.

The DCF analysis is a forward-looking enterprise valuation methodology that estimates the value of an assets or business by calculating the present value of expected future cash flows by that asset or business. The basis of the DCF analysis was the Company’s prepared projections which included a variety of estimates and assumptions, such as pricing and demand for coal. The Company’s pricing was based on its view of the market taking into account third party forward pricing curves adjusted for the quality of products sold by the Company. While the Company considers such estimates and assumptions reasonable, they are inherently subject to significant business, economic and competitive uncertainties, many of which are beyond the Company’s control and, therefore, may not be realized. Changes in these estimates and assumptions may have a significant effect on the determination of the Company’s enterprise value. The assumptions used in the calculations for the DCF analysis included projected revenue, cost and cash flows for the years ending December 31, 2016 through each respective mine life and represented the Company’s best estimates at the time the analysis was prepared. The DCF analysis was completed using discount rates at a range of estimated weighted average costs of capital ranging from 13.25% to 15.25% . The DCF analysis involves complex considerations and judgments concerning appropriate discount rates. Due to the unobservable inputs to the valuation, the fair value would be considered Level 3 in the fair value hierarchy.

The sum-of-the-parts analysis is a more detailed market multiples approach the values each part of a company’s business separately based upon the enterprise values of selected publicly traded companies that have operating and financial characteristics comparable in certain respects to each part of the reorganized Company. Under this methodology, certain financial multiples and ratios that measure financial performance and value are calculated for each selected comparable company and then applied to the relevant segment of the Company’s financials to imply an enterprise value for the Company.

Accounting Impact of Emergence

Upon emergence in accordance with ASC 852, the Company applied fresh start accounting to its consolidated financial statements as of October 1, 2016 because (i) the reorganization value of the assets of the emerging entity immediately before the date of confirmation was less than the total of all postpetition liabilities and allowed claims and (ii) the holders of the existing voting shares immediately before confirmation received less than 50 percent of the voting shares of the emerging entity. Upon adoption of fresh start accounting, the Company became a new entity for financial reporting purposes reflecting the Successor capital structure. As such, a new accounting basis in the identifiable assets and liabilities assumed was established with no retained earnings or accumulated other comprehensive income (loss) (“OCI”).

The following balance sheet illustrates the impacts of the implementation of the Plan and the application of fresh start accounting, which results in the opening balance sheet of the Successor company.



As of October 1, 2016 (In thousands)	Predecessor (a)			Effect of Plan (b)				Fresh Start Adjustments (c)				Successor
Assets
Current assets
Cash and cash equivalents	$	400,205		$	(199,718	)	(d)	$	—			$	200,487
Short term investments	111,451			—				—				111,451
Restricted cash	81,563			—				—				81,563
Trade accounts receivable	165,522			—				—				165,522
Other receivables	17,227			—				779			(j)	18,006
Inventories	159,410			—				(21,078		)	(k)	138,332
Prepaid royalties	4,805			—				—				4,805
Deferred income taxes	—			—				—				—
Coal derivative assets	2,180			—				—				2,180
Other current assets	36,960			6,367				53,851			(l)	97,178
Total current assets	979,323			(193,351		)		33,552				819,524

Property, plant and equipment, net	3,434,941			—				(2,363,829		)	(m)	1,071,112
Other assets
Prepaid royalties	20,997			—				(20,997		)	(n)	—
Equity investments	164,232			—				(61,606		)	(o)	102,626
Other noncurrent assets	58,569			34,495			(e)	37,503			(p)	130,567
Total other assets	243,798			34,495				(45,100		)		233,193
Total assets	$	4,658,062		$	(158,856	)		$	(2,375,377	)		$	2,123,829

Liabilities and Stockholders’ Equity (Deficit)
Liabilities not subject to compromise
Accounts payable	$	74,595		$	—			$	(250	)	(q)	$	74,345
Accrued expenses and other current liabilities	225,739			(36,331		)	(f)	26,644			(r)	216,052
Current maturities of debt	3,397			3,265			(g)	—				6,662
Total current liabilities	303,731			(33,066		)		26,394				297,059
Long-term debt	30,037			323,235			(g)	—				353,272
Asset retirement obligations	394,699			—				(60,570		)	(s)	334,129
Accrued pension benefits	23,716			—				24,565			(t)	48,281
Accrued other postretirement benefits	87,123			—				24,836			(t)	111,959
Accrued workers’ compensation	119,828			—				74,520			(u)	194,348
Deferred income taxes	—			—				—				—
Other noncurrent liabilities	96,410			—				888			(v)	97,298
Total liabilities not subject to compromise	1,055,544			290,169				90,633				1,436,346

Liabilities subject to compromise	5,278,612			(5,278,612		)	(h)	—				—

Total liabilities	6,334,156			(4,988,443		)		90,633				1,436,346

Stockholders’ equity (deficit)
Common stock, predecessor	2,145			(2,145		)	(i)	—				—
Common stock, successor	—			250			(b)	—				250
Paid-in capital, predecessor	3,056,307			(3,056,307		)	(i)	—				—
Paid-in capital, successor	—			687,233			(b)	—				687,233
Treasury stock, at cost	(53,863		)	53,863			(i)	—				—
Accumulated earnings (deficit)	(4,678,977		)	7,146,693			(i)	(2,467,716		)		—
Accumulated other comprehensive income (loss)	(1,706		)	—				1,706				—
Total stockholders’ equity (deficit)	(1,676,094		)	4,829,587				(2,466,010		)		687,483
Total liabilities and stockholders’ equity (deficit)	$	4,658,062		$	(158,856	)		$	(2,375,377	)		$	2,123,829


(a)	Represents the Predecessor consolidated balance sheet as of October 1, 2016.


(b)	Represents amounts recorded for the implementation of the Plan on the Effective Date. This includes the settlement of liabilities subject to compromise through a combination of cash payments, the issuance of new common stock and warrants and the issuance of new debt. The following is the calculation of the total pre-tax gain on the settlement of the liabilities subject to compromise:



	In thousands
Liabilities subject to compromise	$	5,278,612
Less amounts issued to settle claims:
Common stock (at par) Successor	(250		)
Warrants Successor	(14,822		)
Paid-in capital Successor	(672,411		)
Issuance of Term Loan Successor	(326,500		)
Cash payment to settle claims and professional fees	(122,525		)

Total pre-tax gain on plan effects	$	4,142,104


(c)	Represents the fresh start accounting adjustments required to record the assets and liabilities of the Company at fair value.


(d)	The following table reflects the use of cash at emergence:



	In thousands
Payment to secured lenders	$	43,496
Payments to unsecured creditors	42,399
Final adequate protection payment	36,331
Collateral requirements	31,665
Professional fees	31,630
Other	14,197

Total cash outflow at emergence	$	199,718


(e)	Represents amounts paid for required collateral deposits.


(f)	Represents the final adequate protection payments made to the secured lenders.


(g)	Represents the fair value of the $326.5 million new term loan of which $3.3 million is shown within current maturities of debt.


(h)	Liabilities subject to compromise include unsecured or under-secured liabilities incurred prior to the Chapter 11 filing; and consists of the following:



Previously Reported Balance Sheet Line	In thousands
Debt	$	5,026,806
Accrued expenses and other current liabilities	136,295
Accounts payable	106,297
Other noncurrent liabilities	9,214

Total liabilities subject to compromise	$	5,278,612


(i)	Reflects the impacts of the reorganization adjustments:



	In thousands
Total pre-tax gain on settlement of claims	$	4,142,104
Cancellation of predecessor common stock	2,145
Cancellation of predecessor paid-in capital	3,056,307
Cancellation of predecessor treasury stock	(53,863		)

Net impact on accumulated earnings (deficit)	$	7,146,693


(j)	Represents adjustments to record other receivables at fair value which includes an $0.8 million short-term receivable related to insurance coverage for self-insured workers’ compensation obligations.

(k)

Represents the following fair value adjustments: a $7.3 million increase related to coal inventory which was fair valued at estimated selling prices less the sum of selling costs, shipping costs and a reasonable profit allowance for the selling effort offset by a $28.4 million reduction in critical spare parts inventory. During fresh start accounting, the Company changed its accounting policy with respect to critical spare parts with long lead times; previously these items were valued within inventory, but prospectively, these items will be capitalized within property, plant and equipment when purchased and depreciated over the life of the related equipment.


(l)	Represents the short-term portion of above market coal sales contracts of $71.1 million offset by $11.3 million in reductions related to prepaid balances. The fair value of sales contracts was estimated using a discounted cash flow model and will be amortized into earnings as the coal is shipped throughout the term of the associated contracts.


(m)	Represents a $2.4 billion reduction in property, plant and equipment to estimated fair value as discussed below:



	Predecessor		Fresh Start Adjustments			Successor
(in thousands)
Net Coal Properties	$	2,358,779	$	(1,971,314	)	$	387,465
Net Plant & Equipment	812,888		(405,259		)	407,629
Net Deferred Charges	263,274		12,744			276,018

	$	3,434,941	$	(2,363,829	)	$	1,071,112

The fair value of coal properties was established at $387.5 million utilizing a discounted cash flow model and the market approach. The market approach was used to provide a starting value of the coal mineral reserves without consideration for economic obsolescence. The DCF model was based on assumptions market participants would use in the pricing of these assets as well as projections of revenues and expenditures that would be incurred to mine or maintain these coal reserves through the life of mine. The basis of the DCF analysis was the Company’s prepared projections which included a variety of estimates and assumptions, such as pricing and demand for coal. The Company’s pricing was based on its view of the market taking into account third party forward pricing curves adjusted for the quality of products sold by the Company.

The fair value of plant and equipment was set at $407.6 million utilizing both market and cost approaches. The market approach was used to estimate the value of assets where detailed information for the asset was available and an active market was identified with a sufficient number of sales of comparable property that could be independently verified through reliable sources. The cost approach was utilized where there were limitations in the secondary equipment market to derive values from. The first step in the cost approach is the estimation of the cost required to replace the asset via construction or purchasing a new asset with similar utility adjusting for depreciation due to physical deterioration, functional obsolescence due to technology changes and economic obsolescence due to external factors such as regulatory changes. Useful lives were assigned to all assets based on remaining future economic benefit of each asset.

The fair value of deferred charges represents the corresponding asset related to the asset retirement obligation discussed in item (q) below.


(n)	Represents a fair value adjustment to a long-term prepaid royalty balance that the Company has concluded should not be assigned value based on market conditions and after considering economic obsolescence.

(o)

Represents a fair value adjustment to the Company’s equity investments in Knight Hawk Holdings, LLC, a coal producer in the Illinois Basin; and Dominion Terminal Associates which operates a ground storage-to-vessel coal trans-loading facility in Newport News, Virginia. Equity investments were fair valued in a manner similar to the Company’s wholly-owned subsidiaries using a discounted cash flow model and comparable company approach. The discount rate selected was 14% and due to the unobservable nature of the inputs, the fair values are considered Level 3 in the fair value hierarchy.

(p)

Represents the long-term portion of above market coal sales contracts of $26.0 million and $18.6 million related to a long-term insurance receivable related to insurance coverage for self-insured workers’ compensation obligations partially offset by $13.2 million in reductions related to prepaid balances. The fair value of sales contracts was estimated using a discounted cash flow model and will be amortized into earnings as the coal is shipped throughout the term of the associated contracts.


(q)	Represents a fair value adjustment to miscellaneous accounts payable.

(r)

Represents fair value adjustments for the following: a $27.8 million increase related to the short-term portion of below market sales contracts offset by fair value adjustments to establish the current portion of pension, postretirement and workers’ compensation liabilities. The fair value of sales contracts was estimated using a discounted cash flow model and will be amortized into earnings as the coal is shipped throughout the term of the associated contracts.


(s)	Represents the fair value adjustment related to the Company’s asset retirement obligations which was calculated using discounted cash flow models based on current mine plans using the guidance provided within Accounting Standard Codification 410-20, “Asset Retirement Obligations.” The discount rates ranged from 7.06% to 9.08%.


(t)	Pension and postretirement benefits were fair valued based on plan assets and employee benefit obligations at October 1, 2016. The benefit obligations were computed using the applicable October 1, 2016 discount rates. In conjunction with fresh start accounting, the Company updated its mortality rate table assumptions and corridor assumption.

(u)

Represents fair value adjustments for workers’ compensation benefits, including occupational disease benefits, that were actuarially determined using the guidance provided within Accounting Standard Codification 712, “Non-retirement Post-employment Benefits.” Upon emergence, the Company’s accounting policy is to actuarially calculate this liability. Prior to emergence, the Company had accounted for its liability based on outstanding reserves calculated per third party administrators.

(v)

Represents the following fair value adjustments: $3.9 million increase related to the long-term portion of below market sales contracts partially offset by $3.1 million reduction in miscellaneous noncurrent liabilities. The fair value of sales contracts was estimated using a discounted cash flow model and will be amortized into earnings as the coal is shipped throughout the term of the associated contracts.

Reorganization Items, Net

In accordance with ASC 852, the statement of operations shall portray the results of operations of the reporting entity while it is in Chapter 11. Revenues, expenses (including professional fees), realized gains and losses, and provisions for losses resulting from reorganization and restructuring of the business shall be reported separately as reorganization items.

The Company’s reorganization items, net for the respective periods are as follows:



	Successor			Predecessor
	October 2 through December 31, 2016			January 1 through October 1, 2016			Year Ended December 31, 2015		Year Ended December 31, 2014
(In thousands)
Gain on settlement of claims (per above)	$	—		$	4,142,104		$	—	$	—
Fresh start adjustments, net (per above)	—			(2,466,010		)	—		—
Professional fees	(759		)	(46,053		)	—		—

	$	(759	)	$	1,630,041		$	—	$	—

Professional fees directly related to the reorganization include fees associated with advisors to the Company, certain secured creditors and the Creditors’ Committee. During the Successor period ended December 31, 2016, the Company continued to incur costs related to professional fees that are directly attributable to the reorganization.

Contractual Interest Expense During Bankruptcy

Upon the filing of bankruptcy, the Company discontinued recording interest expense on unsecured debt that was classified as a liability subject to compromise. Actual interest expense recorded on the Predecessor debt subsequent to the Petition Date was $135.9 million for the period January 1 through October 1, 2016; contractual interest during this time was $300.9 million.

Accumulated Other Comprehensive Income (Loss)

12 Months Ended

Dec. 31, 2016

Accumulated Other Comprehensive Income (Loss) [Abstract]

Accumulated Other Comprehensive Income (Loss)

The following items are included in accumulated other comprehensive income (loss):




				Pension,
				Postretirement						Accumulated
				and Other Post-						Other
	Derivative			Employment			Available-for-			Comprehensive
	Instruments			Benefits			Sale Securities			Income (Loss)
	(In thousands)
Predecessor Company
January 1, 2015	$	2,550		$	2,860		$	(2,169	)	$	3,241
Unrealized gains (losses)	3,903			(8,723		)	(3,333		)	(8,153		)
Amounts reclassified from accumulated other comprehensive income (loss)	(6,128		)	5,142			4,083			3,097
December 31, 2015	325			(721		)	(1,419		)	(1,815		)
Unrealized gains (losses)	(138		)	—			701			563
Amounts reclassified from accumulated other comprehensive income (loss)	(316		)	(1,363		)	1,225			(454		)
Fresh start accounting adjustment	129			2,084			(507		)	1,706
October 1, 2016	$	—		$	—		$	—		$	—
Successor Company
Unrealized gains	—			24,067			387			24,454
Amounts reclassified from accumulated other comprehensive income (loss)	—			—			—			—
December 31, 2016	$	—		$	24,067		$	387		$	24,454

The unrealized gain in the successor period is the result of changes in the discount rates used to calculate our pension, postretirement health and occupational disease obligations.

The following amounts were reclassified out of accumulated other comprehensive income (loss) during the respective periods:



Details about accumulated other comprehensive income components	Successor		Predecessor						Line Item in the Consolidated Statement of Operations
	October 2 through December 31, 2016		January 1 through October 1, 2016			Year Ended December 31, 2015
	(in thousands)		(in thousands)
Derivative instruments	$	—	$	397		$	9,575		Revenues
	—		(81		)	(3,447		)	Provision for (benefit from) income taxes
	$	—	$	316		$	6,128		Net of tax

Pension, postretirement and other post-employment benefits
Amortization of prior service credits ¹	$	—	$	7,854		$	8,335
Amortization of net actuarial gains (losses) ¹	—		(6,010		)	(16,369		)
	—		1,844			(8,034		)	Total before tax
	—		(481		)	2,892			Provision for (benefit from) income taxes
	$	—	$	1,363		$	(5,142	)	Net of tax

Available-for-sale securities ²	$	—	$	(2,263	)	$	(6,391	)	Interest and investment income
	—		1,038			2,308			Provision for (benefit from) income taxes
	$	—	$	(1,225	)	$	(4,083	)	Net of tax
¹ Production-related benefits and workers’ compensation costs are included in costs to produce coal.
² The gains and losses on sales of available-for-sale-securities are determined on a specific identification basis.

- Definition

The entire disclosure for comprehensive income, which includes, but is not limited to, 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.

+ References

Reference 1: 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=66004124&loc=d3e689-108580

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=66004124&loc=SL7669619-108580

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=66004124&loc=d3e640-108580

Reference 4: 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=66004124&loc=d3e716-108580

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 16
-URI http://asc.fasb.org/extlink&oid=66004124&loc=d3e709-108580

Reference 6: 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=27012166&loc=d3e187085-122770

Reference 7: 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=66004124&loc=d3e637-108580

Reference 8: 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=66004124&loc=d3e681-108580

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

+ Details

Impairment Charges and Mine Closure Costs

12 Months Ended

Dec. 31, 2016

Impairment Charges and Mine Closure Costs [Abstract]

Impairment Charges and Mine Closure Costs

The following table summarizes the amounts reflected on the line “Asset impairment and mine closure costs” in the consolidated statements of operations:



	Successor		Predecessor
Description	October 2 Through December 31, 2016		January 1 Through October 1, 2016		Year Ended December 31, 2015			Year Ended December 31, 2014
			(In thousands)
Coal lands and mineral rights	$	—	$	74,144	$	2,210,488		$	—
Plant and equipment	—		—		199,107			1,512
Deferred development	—		—		159,474			—
Prepaid royalties	—		3,406		41,990			15,356
Equity investments	—		40,920		21,325			—
Inventories	—		—		66			—
Other	—		10,797		(4,147		)	7,245
Total	$	—	$	129,267	$	2,628,303		$	24,113

January 1 Through October 1, 2016 Impairment Charges

During the period January 1 through October 1, 2016, the Company recorded the following to “Asset impairment and mine closure costs” in the Consolidated Statements of Operations: $74.1 million recorded in the first quarter related to the impairment of coal reserves and surface land in Kentucky that are being leased to a mining company that idled its mining operations; $3.4 million recorded in the first quarter related to the impairment on the portion of an advance royalty balance on a reserve base mined at the Company’s Mountain Laurel operation that will not be recouped; $2.9 million recorded in the first quarter related to an other-than-temporary-impairment charge on an available-for-sale security; a $38.0 million impairment recorded in the second quarter related to the Company’s equity investment in a brownfield bulk commodity terminal on the Columbia River in Longview, Washington as the Company relinquished its ownership rights in exchange for future throughput rights; $7.2 million of severance expense related to headcount reductions during the first half of the year; a $3.6 million curtailment charge related to the Company’s pension, postretirement health and black lung actuarial liabilities due to headcount reductions in the first half of the year.

2015 Impairment Charges

In 2015, as a result of the continued deterioration in thermal and metallurgical coal markets and projections for a muted pricing recovery, certain of the Company’s mine complexes have incurred and are expected to continue to incur operating losses. The Company determined that the further weakening of the pricing environment in the last half of the year and the projected operating losses represented indicators of impairment with respect to certain of its long-lived assets or assets groups. Using current pricing expectations which reflected marketplace participant assumptions, life of mine cash flows were used to determine if the undiscounted cash flows exceeded the current asset values for certain operating complexes in the Company’s Appalachia segment. For multiple operating complexes, the undiscounted cash flows did not exceed the carrying value of the long-lived assets. Discounted cash flows were utilized to reduce the carrying value of those assets to fair value. The discount rate used reflected the then current financial difficulties present in the commodities sector in general and coal mining specifically; the perceived risk of financing coal mining in light of industry defaults; and the lack of an active market for buying or selling coal mining assets. Additionally, the Company determined that the then current market conditions represented an indicator of impairment for certain undeveloped coal properties that were acquired in times of significantly higher coal prices. The then current prices and the significant capital outlay that would have been required to develop these reserves indicated that the carrying value was not recoverable. As a result the Company recorded a $2.6 billion asset impairment charge in the last two quarters of 2015 of which $2.1 billion was recorded during the third quarter and the remaining $0.5 billion was recorded in the fourth quarter. Of the total charge. $2.2 billion was recorded to the Company’s Appalachia segment, with the remaining $0.4 billion recorded to the Company’s Other operating segment. There is no fair value remaining related to the impaired assets.

During the second quarter of 2015, the Company recorded $19.1 million to “Asset impairment and mine closure costs” in the Consolidated Statements of Operations. An impairment charge of $12.2 million related to the portion of an advance royalty balance on a reserve base mined at the Company’s Mountain Laurel, Spruce and Briar Branch operations that was determined would not be recouped based on estimates of sales volume and pricing through the March 2017 recoupment period. Additionally, the Company recorded a $5.6 million impairment charge related to the closure of a higher-cost mining complex serving the metallurgical coal markets.

2014 Impairment Charges

During the Company’s annual budgeting process for 2015 (performed in the fall of 2014), a review of forecasted revenues indicated that the remaining balance of advance royalty payments made on a reserve base supplying the Company’s Mountain Laurel, Spruce Mine and Briar Branch operations would not be recoupable against future royalties payments. Under the lease, any unrecouped advance payment balance at March 31, 2017 will be forfeited by the Company. Based on estimates of sales volumes and pricing through the end of the recoupment period, an impairment charge was recorded during the fourth quarter of 2014 for $15.4 million of the remaining $48.0 million balance that was determined would not be recouped.

In response to weak metallurgical coal markets the Company idled a higher-cost mining complex in the third quarter of 2014 in order to concentrate on metallurgical coal production from its lowest-cost and highest-margin operations. Closure charges of $5.1 million were recognized during the third quarter of 2014 relating to the idling.

Losses from disposed operations resulting from Patriot Coal Bankruptcy	12 Months Ended
	Dec. 31, 2016
Discontinued Operations and Disposal Groups [Abstract]
Losses from disposed operations resulting from Patriot Coal Bankruptcy	Losses from disposed operations resulting from Patriot Coal bankruptcy On December 31, 2005, Arch entered into a purchase and sale agreement with Magnum to sell certain operations. On July 23, 2008, Patriot acquired Magnum. On May 12, 2015, Patriot and certain of its wholly owned subsidiaries (“Debtors”), including Magnum, filed voluntary petitions for reorganization under Chapter 11 of the U.S. Code in the U.S. Bankruptcy Court for the Eastern District of Virginia. Subsequently, on October 28, 2015, Patriot’s Plan of Reorganization was approved, including an authorization to reject their collective bargaining agreements and modify certain union-related retiree benefits. As a result of the Plan of Reorganization, the Company became statutorily responsible for retiree medical benefits pursuant to Section 9711 of the Coal Industry Retiree Health Benefit Act of 1992 for certain retirees of Magnum who retired prior to October 1, 1994. In addition, the Company has provided surety bonds to Patriot related to permits that were sold to an affiliate of Virginia Conservation Legacy Fund, Inc. (“VCLF”). Should VCLF not perform required reclamation, the Company would incur losses under the bonds and related indemnity agreements. The Company recognized $116.3 million in losses in 2015 related to the previously disposed operations as a result of the Patriot Coal bankruptcy. On November 22, 2016, Arch entered into a”Collateral Use Agreement” which caused the replacement, substitution and discharge of reclamation surety bonds related to the former Magnum properties placed by Arch in exchange for a collateral release of $20 million held by the bonding company to VCLF.

- Definition

The entire disclosure related to a disposal group. Includes, but is not limited to, a discontinued operation, disposal classified as held-for-sale or disposed of by means other than sale or disposal of an individually significant component.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=65878427&loc=SL51721533-107759

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 4B
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721665-107760

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5C
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721675-107760

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 3A
-URI http://asc.fasb.org/extlink&oid=64862545&loc=SL51724579-110230

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 4A
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721663-107760

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64862545&loc=d3e2941-110230

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
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-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=64827811&loc=d3e1361-107760

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
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-Section 50
-Paragraph 5B
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721673-107760

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
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-Section 50
-Paragraph 3A
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721659-107760

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5A
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721671-107760

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5D
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721677-107760

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
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-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64827811&loc=d3e1474-107760

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721683-107760

+ Details

Inventories

12 Months Ended

Dec. 31, 2016

Inventory Disclosure [Abstract]

Inventories

Inventories consist of the following:



	Successor		Predecessor
	December 31, 2016		December 31, 2015
(In thousands)
Coal	$	37,268	$	85,043
Repair parts and supplies	76,194		111,677
	$	113,462	$	196,720

The repair parts and supplies are stated net of an allowance for slow-moving and obsolete inventories of $0.0 million at December 31, 2016 and $6.0 million at December 31, 2015.

Investments in Available-for-Sale Securities

12 Months Ended

Dec. 31, 2016

Available-for-sale Securities [Abstract]

Investments in Available-for-Sale Securities

The Company has invested primarily in highly liquid investment-grade corporate bonds. These investments are held in the custody of a major financial institution. These securities, along with the Company’s investments in marketable equity securities, are classified as available-for-sale securities and, accordingly, the unrealized gains and losses are recorded through other comprehensive income.

The Company’s investments in available-for-sale marketable securities are as follows:



	Successor
	December 31, 2016
										Balance Sheet
			Gross		Gross					Classification
			Unrealized		Unrealized			Fair		Short-Term		Other
	Cost Basis		Gains		Losses			Value		Investments		Assets
	(In thousands)
Available-for-sale:
Corporate notes and bonds	$	88,161	$	—	$	(89	)	$	88,072	$	88,072	$	—
Equity securities	1,749		388		—			2,137		—		2,137
Total Investments	$	89,910	$	388	$	(89	)	$	90,209	$	88,072	$	2,137



	Predecessor
	December 31, 2015
										Balance Sheet
			Gross		Gross					Classification
			Unrealized		Unrealized			Fair		Short-Term		Other
	Cost Basis		Gains		Losses			Value		Investments		Assets
	(In thousands)
Available-for-sale:
U.S. government and agency securities	$	10,007	$	—	$	(12	)	$	9,995	$	9,995	$	—
Corporate notes and bonds	190,496		—		(299		)	190,197		190,197		—
Equity securities	3,938		668		(2,888		)	1,718		—		1,718
Total Investments	$	204,441	$	668	$	(3,199	)	$	201,910	$	200,192	$	1,718

The aggregate fair value of investments with unrealized losses that had been owned for less than a year was $47.6 million and $184.6 million at December 31, 2016 and 2015, respectively. The aggregate fair value of investments with unrealized losses that have been owned for over a year was $40.4 million and $15.8 million at December 31, 2016 and 2015, respectively.

The debt securities outstanding at December 31, 2016 have maturity dates ranging from the first quarter of 2017

through the fourth quarter of 2017. The Company classifies its investments as current based on the nature of the investments and their availability to provide cash for use in current operations, if needed.

- Definition

The entire disclosure for investments in certain debt and equity securities.

+ References + Details

Equity Method Investments and Membership Interests in Joint Ventures

12 Months Ended

Dec. 31, 2016

Equity Method Investments and Joint Ventures [Abstract]

Equity Method Investments and Membership Interests in Joint Ventures

The Company accounts for its investments and membership interests in joint ventures under the equity method of accounting if the Company has the ability to exercise significant influence, but not control, over the entity. Equity method investments are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the investments may not be recoverable.

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



(In thousands)	Knight Hawk			DTA			Millennium			Tongue River			Other			Total
Predecessor Company
January 1, 2014	$	152,806		$	14,137		$	35,894		$	18,419		$	200		$	221,456
Advances to (distributions from) affiliates, net	(12,603		)	3,774			6,742			2,541			3,600			4,054
Equity in comprehensive income (loss)	18,274			(4,173		)	(2,413		)	(220		)	(1,136		)	10,332
December 31, 2014	158,477			13,738			40,223			20,740			2,664			235,842
Advances to (distributions from) affiliates, net	(29,862		)	3,207			7,052			913			330			(18,360		)
Equity in comprehensive income (loss)	22,977			(3,706		)	(9,686		)	(328		)	(1,278		)	7,979
Impairment of equity investment	—			—			—			(21,325		)				(21,325		)
Sale of equity investment	—			—			—			—			(2,259		)	(2,259		)
December 31, 2015	151,592			13,239			37,589			—			(543		)	201,877
Advances to (distributions from) affiliates, net	(8,374		)	1,474			1,966			—			—			(4,934		)
Equity in comprehensive income (loss)	9,033			(2,095		)	(1,530		)	—			(94		)	5,314
Impairment of equity investment	—			—			(38,025		)	—			—			(38,025		)
Fresh start accounting adjustment	(58,251		)	(4,018		)	—			—			662			(61,607		)
October 1, 2016	$	94,000		$	8,600		$	—		$	—		$	25		$	102,625
Successor Company
Advances to (distributions from) affiliates, net	(9,076		)	822			—			—			—			(8,254		)
Equity in comprehensive income (loss)	2,569			(841		)	—			—			(25		)	1,703

December 31, 2016	$	87,493		$	8,581		$	—		$	—		$	—		$	96,074

The Company holds a 49% equity interest in Knight Hawk Holdings, LLC (“Knight Hawk”), a coal producer in the Illinois Basin.

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 previously held 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. Millennium continues to work on obtaining the required approvals and necessary permits to complete dredging and other upgrades to ship coal, alumina and cementitious material from the terminal. During the second quarter of 2016, the Company recorded an impairment charge of $38.0 million representing the entire value of its equity investment as the Company relinquished its ownership rights in exchange for future throughput rights through the facility when completed.

The Company holds a 35% 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 had 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. During the third quarter of 2015, the Company recorded an impairment charge of $21.3 million representing the entire value of the Company’s investment in the project; the impairment charge is included on the line “Asset impairment and mine closure costs.”

The Company is not required to make any future contingent payments related to development financing for any of its equity investees.

Sales Contracts

12 Months Ended

Dec. 31, 2016

Acquired Sales Contracts [Abstract]

Sales Contracts

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



	Successor								Predecessor
	December 31, 2016								December 31, 2015
	Assets			Liabilities			Net Total		Assets			Liabilities			Net Total
	(In thousands)								(In thousands)
Original fair value	$	97,196		$	31,742				$	131,299		$	166,697
Accumulated amortization	(25,625		)	(24,829		)			(130,839		)	(151,354		)
Total	$	71,571		$	6,913		$	64,658	$	460		$	15,343		$	(14,883	)
Balance Sheet classification:
Other current	$	59,702		$	5,114				$	460		$	3,852
Other noncurrent	$	11,869		$	1,799				$	—		$	11,491

The Company anticipates amortization of sales contracts, based upon expected shipments in the next five years, to be expense of approximately $54.3 million in 2017, $10.7 million in 2018, $1.1 million in 2019, and income of $0.6 million in 2020 and $0.1 million in 2021.

Derivatives

12 Months Ended

Dec. 31, 2016

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivatives

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 45 to 50 million gallons of diesel fuel for use in its operations during 2017. To protect the Company’s cash flows from increases in the price of diesel fuel for its operations, the Company may use forward physical diesel purchase contracts and purchase out-of-the-money heating oil call options to protect against substantial increases in pricing. At December 31, 2016, the Company had heating oil call options for approximately 30.7 million gallons at an average strike price of $1.72.

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, 2016, the Company held derivatives for risk management purposes that are expected to settle in the following years:



(Tons in thousands)	2017	2018	Total
Coal sales	540	—	540
Coal purchases	480	—	480

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 unrecognized gains of $0.2 million in the trading portfolio are expected to be realized in 2017.

Tabular derivatives disclosures

The Company has master netting agreements with all of its counterparties which 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, and not 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:



	Successor								Predecessor
	December 31, 2016								December 31, 2015
Fair Value of Derivatives	Asset			Liability					Asset			Liability
(In thousands)	Derivative			Derivative					Derivative			Derivative
Derivatives Designated as Hedging Instruments
Coal	$	—		$	(15	)			$	4		$	(20	)

Derivatives Not Designated as Hedging Instruments
Heating oil -- diesel purchases	4,646			—					1,017			—
Coal held for trading purposes, exchange traded swaps and futures	68,948			(68,740		)			110,653			(104,814		)
Coal -- risk management	475			(580		)			3,912			(1,947		)
Natural gas	86			(13		)			494			(247		)
Total	74,155			(69,333		)			116,076			(107,008		)
Total derivatives	74,155			(69,348		)			116,080			(107,028		)
Effect of counterparty netting	(69,247		)	69,247					(107,028		)	107,028
Net derivatives as classified in the balance sheets	$	4,908		$	(101	)	$	4,807	$	9,052		$	—		$	9,052



		Successor			Predecessor
		December 31, 2016			December 31, 2015
Net derivatives as reflected on the balance sheets
Heating oil	Other current assets	$	4,646		$	1,017
Coal	Coal derivative assets	262			8,035
	Accrued expenses and other current liabilities	(101		)	—
		$	4,807		$	9,052

The Company had a current asset for the right to reclaim cash collateral of $2.8 million and $1.7 million at December 31, 2016 and 2015, 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:

Derivatives used in Cash Flow Hedging Relationships (in thousands)

For the noted periods,



		Gain (Loss) Recognized in Other Comprehensive Income (Effective Portion)
		Successor		Predecessor
		October 2 through December 31, 2016		January 1 through October 1, 2016			Year Ended December 31, 2015			Year Ended December 31, 2014
Coal sales	⁽¹⁾	$	—	$	(672	)	$	12,816		10,842
Coal purchases	⁽²⁾	—		536			(6,718		)	(5,097		)
		$	—	$	(136	)	$	6,098		$	5,745


		Gains (Losses) Reclassified from Other Comprehensive Income into Income (Effective Portion)
		Successor		Predecessor
		October 2 through December 31, 2016		January 1 through October 1, 2016			Year Ended December 31, 2015			Year Ended December 31, 2014
Coal sales		$	—	$	1,634		$	18,635		$	5,336
Coal purchases		—		(1,237		)	(9,060		)	(2,693		)
		$	—	$	397		$	9,575		$	2,643

No ineffectiveness or amounts excluded from effectiveness testing relating to the Company’s cash flow hedging relationships were recognized in the results of operations in the Successor period from October 2 through December 31, 2016, the Predecessor period from January 1 through October 1, 2016, and for the Predecessor years ended December 31, 2015, and 2014.

Derivatives Not Designated as Hedging Instruments (in thousands)

For the noted periods,



		Gain (Loss) Recognized
		Successor			Predecessor
		October 2 through December 31, 2016			January 1 through October 1, 2016			Year Ended December 31, 2015			Year Ended December 31, 2014
Coal — unrealized	⁽³⁾	$	(408	)	$	(1,662	)	$	(3,883	)	$	430
Coal — realized	⁽⁴⁾	$	116		$	(476	)	$	3,236		$	5,956
Heating oil — diesel purchases	⁽⁴⁾	$	827		$	826		$	(8,294	)	$	(7,848	)
Heating oil — fuel surcharges	⁽⁴⁾	$	—		$	—		$	—		$	(405	)
Natural gas		$	(91	)	$	(463	)	$	878		$	—
Foreign currency		$	(9	)	$	(451	)	$	(887	)	$	—

Location in statement of operations:

(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 an immaterial amount for the period October 2 through December 31, 2016 and $0.9 million for the period January 1 through October 1, 2016; and net unrealized and realized gains of $5.7 million, and $3.2 million during the years ended December 31, 2015 and 2014, respectively, related to its trading portfolio, which are included in the caption “Change in fair value of coal derivatives and coal trading activities, net” in the accompanying consolidated statements of operations, and are not included in the previous tables reflecting the effects of derivatives on measures of financial performance.

Based on fair values at December 31, 2016, amounts on derivative contracts designated as hedge instruments in cash flow hedges expected to be reclassified from other comprehensive income into earnings during the next twelve months are immaterial.

- Definition

The entire disclosure for derivative instruments and hedging activities including, but not limited to, risk management strategies, non-hedging derivative instruments, assets, liabilities, revenue and expenses, and methodologies and assumptions used in determining the amounts.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 45
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-URI http://asc.fasb.org/extlink&oid=6441202&loc=d3e80720-113993

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+ Details

Accrued Expenses and Other Current Liabilities

12 Months Ended

Dec. 31, 2016

Accrued Expenses and Other Current Liabilities [Abstract]

Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consist of the following:



	Successor		Predecessor
	December 31, 2016		December 31, 2015
(In thousands)
Payroll and employee benefits	$	58,468	$	58,423
Taxes other than income taxes	92,733		104,755
Interest	8,032		119,785
Sales contracts	5,114		3,852
Workers’ compensation	15,184		16,875
Asset retirement obligations	19,515		13,795
Other	6,194		11,965
	$	205,240	$	329,450

Debt and Financing Arrangements

12 Months Ended

Dec. 31, 2016

Debt Disclosure [Abstract]

Debt and Financing Arrangements



	Successor		Predecessor
	December 31, 2016		December 31, 2015
(In thousands)
Term loan due 2021 ($325.7 million face value)	$	325,684	$	—
Term loan due 2018 ($1.9 billion and $1.93 billion face value, respectively)	—		1,875,429
7.00% senior notes due 2019 at par	—		1,000,000
8.00% senior secured notes due 2019 at par	—		350,000
9.875% senior notes ($375.0 million face value) due 2019	—		365,600
7.25% senior notes due 2020 at par	—		500,000
7.25% senior notes due 2021 at par	—		1,000,000
Other	37,195		47,134
Debt issuance costs	—		(64,857		)
	362,879		5,073,306
Less current maturities of debt	11,038		5,042,353
Long-term debt	$	351,841	$	30,953

Successor Company Debt

New First Lien Debt Facility

Borrowings under the New First Lien Debt Facility bear interest at a per annum rate equal to, at the option of Arch Coal, either (i) a London interbank offered rate plus an applicable margin of 9%, subject to a 1% LIBOR floor (the “LIBOR Rate”), or (ii) a base rate plus an applicable margin of 8%. Interest payments will be payable in cash, unless Arch Coal’s liquidity (as defined therein) after giving effect to the applicable interest payment would not exceed $300 million, in which case interest may be payable in kind (any such interest that is paid in kind, the “PIK Interest”). The term loans provided under the New First Lien Debt Facility (the “Term Loans”) are subject to quarterly principal amortization payments in an amount equal $816,250. To the extent any interest is paid as PIK Interest on any interest payment date, the amount of the Term Loans in respect of which such PIK Interest is payable will be deemed to have accrued additional interest over the preceding interest period at 1.00%, which additional interest will be capitalized and added to the principal amount of outstanding Term Loans. The New First Lien Debt Facility is guaranteed by all existing and future wholly owned domestic subsidiaries of Arch Coal (collectively, the “Subsidiary Guarantors” and, together with Arch Coal, the “Exit Loan Parties”), subject to customary exceptions, and is secured by first priority security interests on substantially all assets of the Exit Loan Parties, including 100% of the voting equity interests of directly owned domestic subsidiaries and 65% of the voting equity interests of directly owned foreign subsidiaries, subject to customary exceptions. Arch Coal has the right to prepay Term Loans at any time and from time to time in whole or in part without premium or penalty, upon written notice, except that any prepayment of Term Loans that bear interest at the LIBOR Rate other than at the end of the applicable interest periods therefor shall be made with reimbursement for any funding losses and redeployment costs of the Lenders resulting therefrom. The New First Lien Debt Facility is subject to certain usual and customary mandatory prepayment events, including 100% of net cash proceeds of (i) debt issuances (other than debt permitted to be incurred under the terms of the New First Lien Debt Facility) and (ii) non-ordinary course asset sales or dispositions, subject to customary thresholds, exceptions and reinvestment rights. The New First Lien Debt Facility contains customary affirmative covenants and representations. The New First Lien Debt Facility also contains customary negative covenants, which, among other things, and subject to certain exceptions, include restrictions on (i) indebtedness, (ii) liens and guaranties, (iii) liquidations, mergers, consolidations, acquisitions, (iv) disposition of assets or subsidiaries, (v) affiliate transactions, (vi) creation or ownership of certain subsidiaries, partnerships and joint ventures, (vii) continuation of or change in business, (viii) restricted payments, (ix) prepayment of subordinated indebtedness, (x) restrictions in agreements on dividends, intercompany loans and granting liens on the collateral, (xi) loans and investments, (xii) changes in organizational documents, (xiii) transactions with respect to bonding subsidiaries and (xiv) hedging transactions. The New First Lien Debt Facility does not contain any financial maintenance covenant. The New First Lien Debt Facility contains customary events of default, subject to customary thresholds and exceptions, including, among other things, (i) non-payment of principal and non-payment of interest and fees, (ii) a material inaccuracy of a representation or warranty at the time made, (iii) a failure to comply with any covenant, subject to customary grace periods in the case of certain affirmative covenants, (iv) cross-events of default to indebtedness of at least $35 million, (v) cross-events of default to surety, reclamation or similar bonds securing obligations with an aggregate face amount of at least $50 million, (vi) uninsured judgments in excess of $35 million, (vii) any loan document shall cease to be a legal, valid and binding agreement, (viii) uninsured losses or proceedings against assets with a value in excess of $35 million, (ix) ERISA events, (x) a change of control or (xi) bankruptcy or insolvency proceedings relating to Arch Coal or any material subsidiary of Arch Coal. The New First Lien Debt Facility will mature on the date that is five years after the Effective Date.

Securitization Facility

On the Effective Date, Arch Coal extended and amended its existing $200 million trade accounts receivable securitization facility provided to Arch Receivable Company, LLC, a non-Debtor special-purpose entity that is a wholly owned subsidiary of Arch Coal (“Arch Receivable”) (the “Extended Securitization Facility”), which continues to support the issuance of letters of credit and reinstates Arch Receivable’s ability to request cash advances, as existed prior to the filing of the voluntary petitions for relief under the Bankruptcy Code. Pursuant to the Extended Securitization Facility, the Debtors agreed to a revised schedule of fees payable to the administrator and the providers of the Extended Securitization Facility. The Extended Securitization Facility will terminate at the earliest of (i) three years from the Effective Date, (ii) if the Liquidity (defined in the Extended

Securitization Facility and consistent with the definition in the New First Lien Debt Facility) is less than $175 million for a period of 60 consecutive days, the date that is the 364th day after the first day of such 60 consecutive day period and (iii) the occurrence of certain predefined events substantially consistent with the existing transaction documents. Under the Extended Securitization Facility, Arch Receivable and certain of the Reorganized Debtors (as defined above) party to the Extended Securitization Facility have granted to the administrator of the Extended Securitization Facility a first priority security interest in eligible trade accounts receivable generated by such Debtors from the sale of coal and all proceeds thereof. As of December 31, 2016, letters of credit totaling $154.4 million were outstanding under the Extended Securitization Facility and the borrowing base was $83.4 million. As a result, cash collateral of $71.0 million has been placed in the Extended Securitization Facility at December 31, 2016 and there is no availability for borrowings.

Predecessor Company Debt

The following debt instruments were fully discharged by the Bankruptcy Court:

•7.00% Senior Notes due 2019;

•7.25% Senior Notes due 2020;

•7.25% Senior Notes due 2021;

•9.875% Senior Notes due 2019;

•8.00% Second Lien Notes due 2019;

•Term loan due 2018;

For additional information see Note 3, “Emergence from Bankruptcy and Fresh Start Accounting.”

Debt Maturities

The contractual maturities of debt as of December 31, 2016 are as follows:



Year	(In thousands)
2017	$	11,038
2018	10,324
2019	11,479
2020	11,761
2021	317,987
Thereafter	290
	$	362,879

Financing Costs

The Company paid financing costs of $23.0 million during the period January 1 through October 1, 2016; and zero and $4.5 million during the years ended December 31, 2015 and 2014, respectively, in conjunction with its financing activities.

The Company incurred $2.2 million of legal fees and financial advisory fees associated with debt restructuring activities in during the period January 1 through October 1, 2016. Additionally, the Company incurred $24.2 million of legal fees and financial advisory fees associated with debt restructuring activities during 2015. During the year ended December 31, 2015, the Company wrote off $3.7 million of deferred financing costs related to the termination of the revolver facility. All amounts have been reflected in the line, “Net loss resulting from early retirement and refinancing of debt” in the Consolidated Statement of Operations.

Taxes

12 Months Ended

Dec. 31, 2016

Income Tax Disclosure [Abstract]

Taxes

Under the Plan, the Company’s pre-petition equity, bank related debt and certain other obligations were cancelled and extinguished. Absent an exception, a debtor recognizes cancellation of debt income (CODI) upon discharge of its outstanding indebtedness for an amount of consideration that is less than its adjusted issue price. In accordance with Internal Revenue Code (IRC) Section 108, the Company excluded the amount of discharged indebtedness from taxable income since the IRC provides that a debtor in a bankruptcy case may exclude CODI from income but must reduce certain tax attributes by the amount of CODI realized as a result of the consummation of a plan of reorganization. The amount of CODI realized by a taxpayer is the adjusted issue price of any indebtedness discharged less than the sum of (i) the amount of cash paid, (ii) the issue price of any new indebtedness issued, and (iii) the fair market value the fair market value of any other consideration, including equity, issued.

CODI from the discharge of indebtedness was $3,353 million. As a result of the CODI and in accordance with IRC rules, the Company reduced its gross federal net operating loss (NOL) carryovers $3,015 million, its alternative minimum tax (AMT) credits $92 million, its capital loss carryforwards $59.2 million and the tax basis in certain assets $3.2 million. The Company was able to retain $931.1 million of gross federal NOLs, $22.8 million of AMT credit and $5.9 million of capital loss carryforwards following the bankruptcy.

Due to changes in ownership that occurred in connection with the Company’s emergence from bankruptcy, there was a change in ownership for purposes of IRC Section 382. Section 382 provides a combined annual limitation with respect to the ability of a corporation to use its NOLs, AMT credits and capital loss carryforwards generated before the ownership change against future taxable income. The Company’s annual limit under IRC section 382 is estimated to be $29.8 million. The Company had a net unrealized built-in gain at the time of the ownership change, therefore, certain built-in gains recognized within five years after the ownership change will increase the annual IRC section 382 limit for the five year recognition period beginning October 1, 2016 through September 30, 2021. There is significant uncertainty surrounding which assets with built-in gain will be realized within the five year period following the Company’s emergence from bankruptcy and allow the Company to realize the incremental net operating losses and credit in excess of the base 382 limitation. The Company is reflecting a deferred tax asset for the full amount of the net operating losses and credit carryforwards. If at some point in time it becomes evident that some portion of the deferred tax assets will not be realizable, the deferred tax asset, and offsetting valuation allowance will be reduced.

The Company is subject to U.S. federal income tax as well as income tax in multiple state jurisdictions. The tax years 2002 through 2016 remain open to examination for U.S. federal income tax matters and 2004 through 2016 remain open to examination for various state income tax matters.

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



	Successor			Predecessor
	October 2 through December 31, 2016			January 1 through October 1, 2016			Year Ended December 31, 2015			Year Ended December 31, 2014
(In thousands)
Current:
Federal	$	—		$	—		$	—		$	—
State	(252		)	7			3			25
Total current	(252		)	7			3			25
Deferred:
Federal	1,352			(4,720		)	(329,393		)	18,535
State	56			87			(43,990		)	7,074
Total deferred	1,408			(4,633		)	(373,383		)	25,609
	$	1,156		$	(4,626	)	$	(373,380	)	$	25,634

A reconciliation of the statutory federal income tax provision (benefit) at the statutory rate to the actual provision for (benefit from) income taxes follows:



	Successor			Predecessor
	October 2 through December 31, 2016			January 1 through October 1, 2016			Year Ended December 31, 2015			Year Ended December 31, 2014
(In thousands)
Income tax provision (benefit) at statutory rate	$	12,112		$	433,109		$	(1,150,283	)	$	(186,452	)
Percentage depletion allowance	(4,292		)	(3,681		)	(19,035		)	(12,692		)
State taxes, net of effect of federal taxes	633			(46,122		)	(76,445		)	(3,903		)
Reversal of cancellation of indebtedness income	—			(1,493,162		)	—			—
Worthless stock deduction	—			(80,077		)	—			—
Change in valuation allowance	(7,655		)	1,185,326			865,146			226,929
Other, net	358			(19		)	7,237			1,752
	$	1,156		$	(4,626	)	$	(373,380	)	$	25,634

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:



	Successor			Predecessor
	December 31, 2016			December 31, 2015
(In thousands)
Deferred tax assets:
Net operating loss carryforwards	$	376,293		$	1,086,332
Alternative minimum tax credit carryforwards	22,798			120,994
Investment in tax partnerships & corporations	604,914			—
Reclamation and mine closure	—			121,276
Goodwill	5,135			38,671
Workers’ compensation	—			42,835
Share based compensation	—			22,612
Sales contracts	—			17,466
Retiree benefit plans	4,013			16,996
Advance royalties	—			18,751
Losses from disposed operations resulting from Patriot Coal bankruptcy	—			39,287
Other, primarily accrued liabilities	30,103			45,303
Gross deferred tax assets	1,043,256			1,570,523
Valuation allowance	(1,021,553		)	(1,135,399		)
Total deferred tax assets	21,703			435,124
Deferred tax liabilities:
Plant and equipment	7,332			389,169
Deferred development	—			41,047
Sales contracts	12,658			—
Other	1,600			4,706
Total deferred tax liabilities	21,590			434,922
Net deferred (asset) liability	(113		)	(202		)

The Company has gross federal net operating loss carryforwards for regular income tax purposes of $931.1 million at December 31, 2016 that will expire between 2022 and 2036. The Company has an alternative minimum tax credit carryforward of $22.8 million at December 31, 2016, which has no expiration date and can be used to offset future regular tax in excess of the alternative minimum tax. The future annual usage of NOLs and AMT credit will be limited under IRC section 382.

As part of our efforts to create operational efficiency leading up to and through the bankruptcy process, we have consolidated our mining operations and land management into a partnership structure to match our legal form with the Company’s streamlined operations during 2016. As such, deferred taxes related to those operations are now reported based upon the book and tax outside basis difference in the partnership interests as provided in ASC 740-30-25-7, which results in a different basis of presentation that was used in 2015 under our prior legal structure.

As recent cumulative losses constitute significant negative evidence with regards to future taxable income, the Company has relied solely on the expected reversal of taxable temporary differences to support the future realization of its deferred tax assets. The Company performs a detailed scheduling process of its net taxable temporary differences.

At December 31, 2014, all deductible temporary differences were expected to be realized as there were sufficient deferred tax liabilities within the same jurisdiction and of the same character that are available to offset them. Valuation allowances were established for federal and state net operating losses and tax credits that were not offset by the reversal of other net taxable temporary differences before the expiration of the attribute.

At December 31, 2015, additional losses were realized relating primarily to financial conditions and asset impairment charges. As a result, the expected reversal of taxable temporary differences were not sufficient to support the future realization of the deferred tax assets and an additional $865.1 million valuation allowance was recorded. Net deferred tax assets of $1,135 million were completely offset by a valuation allowance.

At December 31, 2016, additional tax losses were realized primarily as a result of the non-recognition of CODI under section 108 of the IRC by the Predecessor entity. As a result, the expected reversal of taxable temporary differences were not sufficient to support the future realization of the deferred tax assets and an additional $1,185 million valuation allowance was recorded to the provision. Offsetting this increase was a net reduction in the valuation allowance of $1,289 million which did not impact the provision. This reduction was primarily the result of a decrease in NOLs and AMT credits due to the IRC section 108 offset rules. Net deferred tax assets of $1,022 million are completely offset by a valuation allowance.

A reconciliation of the beginning and ending amounts of gross unrecognized tax benefits follows:



		(In thousands)
Balance at	January 1, 2014	$	31,789
Additions based on tax positions related to the current year		2,920
Balance at	December 31, 2014	34,709
Additions based on tax positions related to the current year		4,168
Balance at	December 31, 2015	38,877
Additions for tax positions of prior years		2,979
Additions for tax positions related to the current year		2,709
Reductions as a result of bankruptcy		(37,110		)
Balance at	December 31, 2016	$	7,455

If recognized, the entire amount of the gross unrecognized tax benefits at December 31, 2016 would affect the effective tax rate.

As a result of the bankruptcy, federal and state governments are precluded from assessing additional tax in audits of tax periods ending prior to bankruptcy. As a result, the Company has released $37.1 million of gross unrecognized tax benefits for years 2015 and prior. These gross unrecognized tax benefits are fully offset by a corresponding release in valuation allowance.

The Company recognizes interest and penalties related to unrecognized tax benefits in income tax expense. The Company had accrued interest and penalties of $0.5 million and $1.7 million at December 31, 2016 and 2015, respectively. In the next 12 months, no gross unrecognized tax benefits are expected to be reduced due to the expiration of the statute of limitations.

Asset Retirement Obligations

12 Months Ended

Dec. 31, 2016

Asset Retirement Obligation [Abstract]

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:



	Successor			Predecessor
	October 2 through December 31, 2016			January 1 through October 1, 2016			Year Ended December 31, 2015
(In thousands)
Balance at beginning of period (including current portion)	$	354,326		$	410,454		$	418,118
Accretion expense	7,634			24,321			33,680
Obligations of divested operations	—			(14,702		)	(334		)
Adjustments to the liability from changes in estimates	—			3,003			(28,570		)
Liabilities settled	(5,218		)	(11,087		)	(12,440		)
Fresh start accounting adjustment	—			(57,663		)	—
Balance at period end	$	356,742		$	354,326		$	410,454
Current portion included in accrued expenses	(19,515		)	(17,290		)	(13,795		)
Noncurrent liability	$	337,227		$	337,036		$	396,659

As of December 31, 2016, the Company had $528.3 million in surety bonds outstanding and $21.3 million in letters of credit to secure reclamation bonding obligations. Additionally, the Company has posted $33.4 million in cash as collateral related to reclamation surety bonds; this amount is recorded within “Noncurrent assets” on the Consolidated Balance Sheet.

Fair Value Measurements

12 Months Ended

Dec. 31, 2016

Fair Value Disclosures [Abstract]

Fair Value Measurements

The hierarchy of fair value measurements assigns a level to fair value measurements based on the inputs used in the respective valuation techniques. 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, U.S. Treasury securities, and coal swaps and 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 U.S. government agency securities and coal commodity contracts 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 (coal and heating oil) valued using modeling techniques, such as Black-Scholes, that require the use of inputs, particularly volatility, that are rarely observable. Changes in the unobservable inputs would not have had a significant impact on the reported Level 3 fair values at December 31, 2016 and 2015.

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



	Successor
	Fair Value at					December 31, 2016
	Total		Level 1				Level 2		Level 3
	(In thousands)
Assets:
Investments in marketable securities	$	90,209	$	2,137			$	88,072	$	—
Derivatives	4,908		262				—		4,646
Total assets	$	95,117	$	2,399			$	88,072	$	4,646
Liabilities:
Derivatives	$	101	$	(8	)		$	—	$	109



	Predecessor
	Fair Value at				December 31, 2015
	Total		Level 1			Level 2		Level 3
	(In thousands)
Assets:
Investments in marketable securities	$	201,910	$	11,713		$	190,197	$	—
Derivatives	9,052		5,597			1,023		2,432
Total assets	$	210,962	$	17,310		$	191,220	$	2,432
Liabilities:
Derivatives	$	—	$	—		$	—	$	—

The Company’s contracts with 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 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.



	Successor			Predecessor
	October 2 through December 31, 2016			January 1 through October 1, 2016			Year Ended December 31, 2015
	(In thousands)			(In thousands)
Balance, beginning of period	$	3,842		$	2,432		$	3,040
Realized and unrealized losses recognized in earnings, net	926			(1,686		)	(8,602		)
Included in other comprehensive income	—			—			(1,341		)
Purchases	1,225			5,021			13,541
Issuances	(34		)	(488		)	(4,046		)
Settlements	(1,422		)	(1,437		)	(160		)
Ending balance	$	4,537		$	3,842		$	2,432

Net unrealized gains of $0.4 million were recognized during the period October 2 through December 31, 2016 related to level 3 financial instruments held on December 31, 2016.

Cash and Cash Equivalents

At December 31, 2016 and 2015, the carrying amounts of cash and cash equivalents approximate their fair value.

Fair Value of Long-Term Debt

At December 31, 2016 and 2015, the fair value of the Company’s debt, including amounts classified as current, was $362.9 million and $937.1 million, respectively. Fair values are based upon observed prices in an active market, when available, or from valuation models using market information, which fall into Level 2 in the fair value hierarchy.

- 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 + Details

Capital Stock

12 Months Ended

Dec. 31, 2016

Equity [Abstract]

Capital Stock

Successor Company

Equity Securities

Under the Plan, 24,589,834 shares of Class A Common Stock and 410,166 shares of Class B Common Stock, par value $.01 per share, were distributed to the secured lenders and to certain holders of general unsecured claims under the Plan on the Effective Date. The Class A Common Stock and Class B Common stock are identical in all respects except that Class B Common Stock shall not be listed by the Company on any national securities exchange registered under Section 6 of the Securities Exchange Act of 1934, as amended. In addition, on the Effective Date, Arch Coal issued Warrants to purchase up to an aggregate of 1,914,856 shares of Class A Common Stock. Arch Coal relied, based on the confirmation order it received from the Bankruptcy Court, on Section 1145(a)(1) of the U.S. Bankruptcy Code to exempt from the registration requirements of the Securities Act of 1933, as amended (i) the offer and sale of Common Stock to the secured lenders and to the general unsecured creditors, (ii) the offer and sale of the Warrants to the holders of claims arising under the Cancelled Notes and (iii) the offer and sale of the Class A Common Stock issuable upon exercise of the Warrants. Section 1145(a)(1) of the Bankruptcy Code exempts the offer and sale of securities under a plan of reorganization from registration under Section 5 of the Securities Act and state laws if three principal requirements are satisfied:


•	the securities must be offered and sold under a plan of reorganization and must be securities of the debtor, of an affiliate participating in a joint plan of reorganization with the debtor or of a successor to the debtor under the plan of reorganization;


•	the recipients of the securities must hold claims against or interests in the debtor; and


•	the securities must be issued in exchange, or principally in exchange, for the recipient’s claim against or interest in the debtor.

See Note 3, “Emergence from Bankruptcy and Fresh Start Accounting” for additional information.

Outstanding Warrants

As of December 31, 2016, holders of warrants had exercised 2,871 of the warrants.

As provided in ASC 825-20, “Financial Instruments,” the warrants are considered equity because they can only be physically settled in Company shares, can be settled in unregistered shares, the Company has adequate authorized shares to settle the outstanding warrants and each warrant is fixed in terms of settlement to one share of Company stock subject only to remote contingency adjustment factors designed to assure the relative value in terms of shares remains fixed.

Predecessor Company

Reverse Stock Split

On August 4, 2015, the Company effected a 1-for-10 reverse stock split of our common stock. Each stockholder’s percentage ownership and proportional voting power remain unchanged as a result of the reverse stock split. All applicable share data, per share amounts and related information in the Consolidated Financial Statements and notes thereto have been adjusted retroactively to give effect to the 1-for-10 reverse stock split.

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SAB Topic 4.E)
-URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74567-122707

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21484-112644

Reference 3: 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(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21488-112644

Reference 5: 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(e))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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(31))
-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 505
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SAB Topic 4.C)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187143-122770

Reference 8: 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(30))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21506-112644

Reference 10: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(d))
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
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Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 30
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6405834&loc=d3e23285-112656

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Preferred Stock
-URI http://asc.fasb.org/extlink&oid=6521494

Reference 15: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 16: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21564-112644

+ Details

Stock-Based Compensation and Other Incentive Plans

12 Months Ended

Dec. 31, 2016

Share-based Compensation [Abstract]

Stock-Based Compensation And Other Incentive Plans

Stock-Based Compensation and Other Incentive Plans

Successor Company

Under the Company’s 2016 Omnibus Incentive Plan (the “Incentive Plan”), 3.0 million shares of the Company’s common stock were 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, 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 impact the shares authorized in the Incentive Plan. Shares available for award under the plan were 2.6 million at December 31, 2016.

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 either vest ratably over or vest at the end of the award’s stated vesting period. Compensation expense is based on the fair value on the grant date and is recorded ratably over the vesting period utilizing the straight-line recognition method. The employee receives cash compensation equal to the amount of dividends that would have been paid on the underlying shares.

Three restricted stock unit awards were granted in the Successor period: two time based awards vesting over one and three years: and one performance based award vesting over a three year period. The time based awards’ grant date fair value was determined based on the stock price at the date of grant. The performance award’s grant date fair value was determined using a Monte Carlo simulation. A volatility of 58% was selected based on comparator companies, and the three year risk free rate was derived from yields on U.S. Government bonds. Information regarding the restricted stock units activity and weighted average grant-date fair value follows:



	Common Shares	Weighted Average Grant-Date Fair Value
(Shares in thousands)
Outstanding at October 2, 2016	—	—
Granted	384	$	72.00
Forfeited	—	—
Canceled	—	—
Unvested outstanding at December 31, 2016	384	$	72.00

The Company recognized expense related to restricted stock units for the period October 2, 2016 through December 31, 2016 of $1.0 million.

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 expense of $1.6 million for the period October 2 through December 31, 2016, $7.2 million for the period January 1 through October 1, 2016, and $7.9 million and $10.1 million for the years ended December 31, 2015 and 2014, respectively. The expense is included primarily in “Selling, general and administrative expenses” in the accompanying consolidated statements of operations.

As part of the plan of reorganization, the Company’s Executive Officers agreed to a $6.0 million reduction in scheduled compensation payouts in 2017. The long term incentive compensation liability was reduced $3.7 million as a fresh start accounting adjustment and is reflected in the Successor period ending December 31, 2016 balance. Amounts accrued and unpaid for all grants under the plan totaled $13.9 million and $17.8 million as of December 31, 2016 and 2015, respectively.

Predecessor Company

On the Effective Date, all shares of our old common stock, including any vested and unvested stock options, restricted stock and restricted stock units were canceled.

Common Stock

Stock options are granted at a strike 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 a least one year from the date of grant. Compensation expense related to stock options for the period January 1, 2016 through October 1, 2016, and for the years ended 2015 and 2014 were $0.2 million, $1.4 million and $3.2 million, respectively. The majority of the cost relating to the stock-based compensation plans is included in “Selling, general and administrative expenses” in the accompanying consolidated statements of operations.

Restricted stock units

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 either vest ratably over or vest at the end of three years. Compensation expense is based on the fair value on the grant date and is recorded ratably over the vesting period. Compensation expense related to restricted stock and restricted stock units for the period January 1, 2016 through October 1, 2016, and for the years ended 2015 and 2014 were $1.9 million, $5.9 million and $5.6 million, respectively. The majority of the cost relating to the stock-based compensation plans is included in “Selling, general and administrative expenses” in the accompanying consolidated statements of operations.

- 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 + Details

Workers' Compensation Expense

12 Months Ended

Dec. 31, 2016

Workers' Compensation Expense

Workers’ Compensation Expense

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 currently provides for federal claims principally through a self-insurance program. The Company is also liable under various state workers’ compensation statutes for occupational disease benefits. The occupational disease benefit obligation represents the present value of the 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 which are calculated using actuarially-based loss rates, loss development factors and discounted based on a risk free rate of 1.74%. Traumatic workers’ compensation claims are insured with varying retentions/deductibles, or through state-sponsored workers’ compensation programs.

Workers’ compensation expense consists of the following components:



	Successor		Predecessor
	October 2 through December 31, 2016		January 1 through October 1, 2016		Year Ended December 31, 2015		Year Ended December 31, 2014
(In thousands)
Self-insured occupational disease benefits:
Service cost	$	1,583	$	3,465	$	4,282	$	1,734
Interest cost	1,126		3,184		3,944		2,914
Net amortization	—		4,325		6,973		(216		)
Total occupational disease	$	2,709	$	10,974	$	15,199	$	4,432
Traumatic injury claims and assessments	3,162		6,628		16,781		19,924
Total workers’ compensation expense	$	5,871	$	17,602	$	31,980	$	24,356

The table below reconciles changes in the occupational disease liability for the respective period.



	Successor			Predecessor
(In thousands)	October 2 through December 31, 2016			January 1 through October 1, 2016			Year Ended December 31, 2015
Beginning of period	$	119,710		$	90,836		$	72,749
Service cost	1,583			3,465			4,282
Interest cost	1,126			3,184			3,944
Curtailments	—			4,156
Actuarial (gain) loss	(9,675		)	—			14,284
Benefit and administrative payments	(1,585		)	(3,728		)	(4,423		)
Fresh start accounting adjustment	—			21,797			—
	$	111,159		$	119,710		$	90,836

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



	Successor	Predecessor
	October 2 through December 31, 2016	January 1 through October 1, 2016	Year Ended December 31, 2015
(Percentages)
Occupational Disease Benefit
Discount rate	4.31	3.80	4.76
Cost escalation rate	N/A	N/A	N/A

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



	Successor		Predecessor
	Year Ended December 31, 2016		Year Ended December 31, 2015
(In thousands)
Occupational disease costs	$	111,159	$	90,836
Traumatic and other workers’ compensation claims	88,593		38,309
Total obligations	199,752		129,145
Less amount included in accrued expenses	15,184		16,875
Noncurrent obligations	$	184,568	$	112,270

As of December 31, 2016, the Company had $146.2 million in surety bonds and letters of credit outstanding to secure workers’ compensation obligations.

The Company’s recorded liabilities include $19.4 million of obligations that are reimbursable under various insurance policies purchased by the company. These insurance receivables are recorded in the balance sheet line items “Other receivables” and “Other noncurrent assets” for $0.8 million and $18.6 million.

Employee Benefit Plans

12 Months Ended

Dec. 31, 2016

Pension and Other Postretirement Benefit Expense [Abstract]

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.

The idling of the Cumberland River mining operations in Appalachia in the third quarter of 2014 reduced the estimated years of future service for the CRCC Scotia Employee Association Pension Plan. On January 1, 2015, the Company’s cash balance and excess plans were amended to freeze new service credits for any new or active employee. These two events triggered curtailment accounting, resulting in an immediate recognition of any unamortized gain or loss and the reduction in the projected benefit obligation which were recorded in the third and fourth quarter of 2014, respectively.

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
	Successor			Predecessor						Successor			Predecessor
	October 2 through December 31, 2016			January 1 through October 1, 2016			Year Ended December 31, 2015			October 2 through December 31, 2016			January 1 through October 1, 2016			Year Ended December 31, 2015
(In thousands)
CHANGE IN BENEFIT OBLIGATIONS
Benefit obligations at beginning of period	$	341,427		$	301,292		$	353,736		$	120,311		$	103,460		$	36,098
Service cost	—			—			9			180			393			866
Interest cost	2,768			9,338			14,604			978			3,223			1,904
Re-entry of former Magnum employees	—			—			—			—			—			85,843
Settlements	(135		)	—			—			—			—			—
Curtailments	—			454			—			—			714			—
Benefits paid	(11,009		)	(8,699		)	(61,955		)	(1,962		)	(8,273		)	(3,646		)
Other-primarily actuarial gain	(19,422		)	—			(5,102		)	(7,640		)	—			(17,605		)
Fresh start accounting adjustments	—			39,042			—			—			20,794
Benefit obligations at end of period	$	313,629		$	341,427		$	301,292		$	111,867		$	120,311		$	103,460
CHANGE IN PLAN ASSETS
Value of plan assets at beginning of period	$	292,726		$	273,499		$	336,709		$	—		$	—		$	—
Actual return on plan assets	(7,899		)	27,811			(1,679		)				—			—
Employer contributions	407			115			424			1,962			8,273			3,646
Benefits paid	(11,009		)	(8,699		)	(61,955		)	(1,962		)	(8,273		)	(3,646		)
Value of plan assets at end of period	$	274,225		$	292,726		$	273,499		$	—		$	—		$	—
Accrued benefit cost	$	(39,404	)	$	(48,701	)	$	(27,793	)	$	(111,867	)	$	(120,311	)	$	(103,460	)
ITEMS NOT YET RECOGNIZED AS A COMPONENT OF NET PERIODIC BENEFIT COST
Prior service credit (cost)	$	—		$	—		$	—		$	—		$	—		$	26,944
Accumulated gain (loss)	6,751			—			(16,769		)	7,640			—			11,313
	$	6,751		$	—		$	(16,769	)	$	7,640		$	—		$	38,257
BALANCE SHEET AMOUNTS
Current liability	$	(520	)	$	(420	)	$	(420	)	$	(10,422	)	$	(8,352	)	$	(3,650	)
Noncurrent liability	(38,884		)	(48,281		)	$	(27,373	)	(101,445		)	(111,959		)	(99,810		)
	$	(39,404	)	$	(48,701	)	$	(27,793	)	$	(111,867	)	$	(120,311	)	$	(103,460	)

Pension Benefits

The accumulated benefit obligation for all pension plans was $313.6 million and $301.3 million at December 31, 2016 and 2015, respectively.

Due to the Company adopting the corridor method of amortizing actuarial gains (losses) during fresh start accounting, it is anticipated there will be no amortization recorded into net periodic benefit cost during 2017.

Other Postretirement Benefit Costs

The following table details the components of pension and postretirement benefit costs (credits):



				Pension Benefits									Other Postretirement Benefits
	Successor			Predecessor									Successor		Predecessor
	October 2 through December 31, 2016			January 1 through October 1, 2016			Year Ended December 31, 2015			Year Ended December 31, 2014			October 2 through December 31, 2016		January 1 through October 1, 2016			Year Ended December 31, 2015			Year Ended December 31, 2014
(In thousands)
Service cost	$	—		$	—		$	9		$	21,478		$	180	$	393		$	866		$	1,649
Interest cost	2,768			9,338			14,604			17,070			978		3,223			1,904			1,841
Curtailments	—			454			—			(25,368		)	—		(970		)	—			—
Settlements	(135		)	—			2,656			646			—		—			—			—
Expected return on plan assets	(4,770		)	(13,623		)	(20,367		)	(23,756		)	—		—			—			—
Amortization of prior service credits	—			—			—			(257		)	—		(7,854		)	(8,335		)	(10,003		)
Amortization of other actuarial losses (gains)	—			3,973			8,850			3,128			—		(849		)	(2,109		)	(761		)
Net benefit cost (credit)	$	(2,137	)	$	142		$	5,752		$	(7,059	)	$	1,158	$	(6,057	)	$	(7,674	)	$	(7,274	)

Schedule of Assumptions Used

The following table provides the weighted average assumptions used to determine the actuarial present value of projected benefit obligations for the respective periods.



	Successor	Predecessor
	October 2 through December 31, 2016	January 1 through October 1, 2016	Year Ended December 31, 2015
(Percentages)
Pension Benefits
Discount rate	3.95	3.39	4.59
Rate of compensation increase	N/A	N/A	N/A

Other Postretirement Benefits
Discount rate	3.93	3.37	4.57
Rate of compensation increase	N/A	N/A	N/A

The following table provides the weighted average assumptions used to determine net periodic benefit cost for the respective periods.



	Successor	Predecessor
	October 2 through December 31, 2016	January 1 through October 1, 2016	Year Ended December 31, 2015	Year Ended December 31, 2014
(Percentages)
Pension Benefits
Discount rate	3.39/3.95	4.59/3.80	4.15/4.61/4.41/4.60	5.08/4.23/4.14
Rate of compensation increase	N/A	N/A	N/A	N/A
Expected return on plan assets	6.85	6.85	7.00	7.75

Other Postretirement Benefits
Discount rate	3.37	4.57/3.80	3.91	4.58
Rate of compensation increase	N/A	N/A	N/A	N/A
Expected return on plan assets	N/A	N/A	N/A	N/A

Schedule of Allocation of Plan Assets

The Company’s pension plan assets at December 31, 2016 and 2015, respectively, are categorized below according to the fair value hierarchy as defined in Note 16, “Fair Value Measurements”:



	Total					Level 1				Level 2				Level 3
	2016			2015		2016		2015		2016		2015		2016		2015
	(In thousands)
Equity Securities:^(A)
U.S. small-cap	$	13,520		$	11,640	$	13,520	$	11,640	$	—	$	—	$	—	$	—
U.S. mid-cap	29,687			28,524		9,422		10,979		20,265		17,545		—		—
U.S. large-cap	70,226			67,244		34,107		33,249		36,119		33,995		—		—
Non-U.S.	18,937			18,785		—		—		18,937		18,785		—		—
Fixed income securities:																—
U.S. government securities^(B)	26,519			18,844		19,973		18,183		6,546		661		—		—
Non-U.S. government securities^(C)	1,567			766		—		—		1,567		766		—		—
U.S. government asset and mortgage backed securities^(D)	1,074			1,056		—		—		1,074		1,056		—		—
Corporate fixed income^(E)	58,191			39,939		—		—		58,191		39,939		—		—
State and local government securities^(F)	6,406			5,725		—		—		6,406		5,725		—		—
Other investments^(I)	26,151			19,869		—		—		6,910		1,234		19,241		18,635
Total	$	252,278		$	212,392	$	77,022	$	74,051	$	156,015	$	119,706	$	19,241	$	18,635
Other fixed income^(G)	35,519
Short-term investments^(H)	8,598
Other liabilities^(J)	(22,170		)
	$	274,225

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

^(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.

^(J)Net payable amount due for pending securities purchased and sold due to broker/dealer.

Schedule of Expected Benefit Payments

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



			Other
	Pension		Postretirement
	Benefits		Benefits
	(In thousands)
2017	$	19,403	$	12,300
2018	21,117		12,716
2019	20,763		13,033
2020	21,209		13,408
2021	21,917		13,763
Next 5 years	102,619		64,920
	$	207,028	$	130,140

Earnings (Loss) Per Common Share (Tables)

12 Months Ended

Dec. 31, 2016

Earnings Per Share [Abstract]

Schedule of Weighted Average Number of Shares

The following table provides the basis for basic and diluted EPS by reconciling the numerators and denominators of the computations:



	Successor	Predecessor
	October 2 through December 31, 2016	January 1 through October 1, 2016	Year Ended December 31, 2015	Year Ended December 31, 2014
(In Thousands)
Weighted average shares outstanding:
Basic weighted average shares outstanding	25,002	21,293	21,285	21,222
Effect of dilutive securities	467	20	—	—

Diluted weighted average shares outstanding	25,469	21,313	21,285	21,222

Leases (Tables)

12 Months Ended

Dec. 31, 2016

Leases [Abstract]

Operating Leases of Lessee Disclosure

Minimum payments due in future years under these agreements in effect at December 31, 2016 are as follows:



	Operating
	Leases		Royalties
	(In thousands)
2017	$	14,653	$	3,994
2018	14,485		6,021
2019	5,321		6,105
2020	2,260		7,147
2021	1,985		7,809
Thereafter	10,317		46,499
	$	49,021	$	77,575

- 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

Risk Concentrations (Tables)

12 Months Ended

Dec. 31, 2016

Risks Concentrations [Abstract]

Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas

The Company’s foreign revenues by geographical location are as follows:



	Successor		Predecessor
	October 2 through December 31, 2016		January 1 through October 1, 2016		Year Ended December 31, 2015		Year Ended December 31, 2014
	(In thousands)		(In thousands)
Europe	$	61,408	$	113,888	$	170,314	$	277,565
Asia	55,634		68,536		96,523		156,057
North America	43,831		56,594		40,315		78,445
Central and South America	13,224		41,861		55,323		20,496
Brokered Sales	—		—		32,848		79,354
Total	$	174,097	$	280,879	$	395,323	$	611,917

Segment Information (Tables)

12 Months Ended

Dec. 31, 2016

Segment Reporting [Abstract]

Schedule Of Operating Segment Results



(In thousands)		PRB		MET		Other Thermal		Corporate, Other and Eliminations			Consolidated
Successor Period	October 2 through December 31, 2016
Revenues		$	275,703	$	200,377	$	97,382	$	2,226		$575,688
Adjusted EBITDAR		55,765		30,819		31,159		(23,246		)	94,497
Depreciation, depletion and amortization		9,949		18,287		3,911		457			32,604
Accretion on asset retirement obligation		5,049		528		540		1,517			7,634
Total assets		446,775		576,793		129,602		983,427			2,136,597
Capital expenditures		934		13,329		684		267			15,214

Predecessor Period	January 1 through October 1, 2016
Revenues		$	726,747	$	437,069	$	213,052	$	21,841		$1,398,709
Adjusted EBITDAR		113,185		11,851		31,448		(69,181		)	87,303
Depreciation, depletion and amortization		100,151		55,311		32,310		3,809			191,581
Accretion on asset retirement obligation		16,940		1,765		1,988		3,628			24,321
Total assets		456,711		619,154		131,173		916,791			2,123,829
Capital expenditures		612		17,296		3,895		60,631			82,434

Predecessor Year Ended	December 31, 2015
Revenues		$	1,448,440	$	637,941	$	428,809	$	58,070		$	2,573,260
Adjusted EBITDAR		281,039		70,450		42,734		(110,426		)	283,797
Depreciation, depletion and amortization		176,257		133,463		47,786		21,839			379,345
Accretion on asset retirement obligation		22,156		2,267		2,658		6,599			33,680
Total assets		1,648,916		772,439		366,610		2,253,916			5,041,881
Capital expenditures		21,228		24,787		11,277		61,732			119,024

Predecessor Year Ended	December 31, 2014
Revenues		$	1,490,377	$	743,973	$	535,783	$	166,986		$	2,937,119
Adjusted EBITDAR		218,731		112,719		78,238		(96,636		)	313,052
Depreciation, depletion and amortization		168,522		163,644		52,991		33,591			418,748
Accretion on asset retirement obligation		20,748		2,089		2,412		7,660			32,909
Total assets		1,762,326		2,339,739		406,296		3,838,001			8,346,362
Capital expenditures		21,399		46,771		14,843		64,273			147,286

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

A reconciliation of segment Adjusted EBITDAR to consolidated income (loss) from continuing operations before income taxes follows:



	Successor			Predecessor
(In thousands)	October 2 through December 31, 2016			January 1 through October 1, 2016			Year Ended December 31, 2015			Year Ended December 31, 2014

Adjusted EBITDAR	$	94,497		$	87,303		$	283,797		$	313,052
Depreciation, depletion and amortization	(32,604		)	(191,581		)	(379,345		)	(418,748		)
Accretion on asset retirement obligations	(7,634		)	(24,321		)	(33,680		)	(32,909		)
Amortization of sales contracts, net	(796		)	728			8,811			13,187
Asset impairment and mine closure costs	—			(129,267		)	(2,628,303		)	(24,113		)
Losses from disposed operations resulting from Patriot Coal bankruptcy	—			—			(116,343		)	—
Interest expense, net	(10,754		)	(133,235		)	(393,549		)	(383,188		)
Net loss resulting from early retirement of debt and debt restructuring	—			(2,213		)	(27,910		)	—
Reorganization items, net	(759		)	1,630,041			—			—
Fresh start coal inventory fair value adjustment	(7,345		)	—			—			—
Income (loss) before income taxes	$	34,605		$	1,237,455		$	(3,286,522	)	$	(532,719	)

Quarterly Selected Financial Data (unaudited) (Tables)

12 Months Ended

Dec. 31, 2016

Quarterly Financial Information Disclosure [Abstract]

Schedule of Quarterly Financial Information



		Predecessor											Successor
Year Ended	December 31, 2016	March 31			June 30			September 30			October 1		October 2 through December 31, 2016
		(a) (b)			(a) (b)			(b)			(b)
(In thousands, except per share data)

Revenues		$	428,106		$	420,298		$	550,305		—		575,688
Gross profit (loss)		$	(53,325	)	$	(56,469	)	$	31,042		—		64,458
Asset impairment and mine closure costs		$	85,520		$	43,701		$	46		—		—
Income (loss) from operations		$	(158,412	)	$	(110,521	)	$	11,795		$	—	$	46,118
Reorganization items, net		$	(3,875	)	$	(21,271	)	$	(20,904	)	$	1,676,091	$	(759	)
Net income (loss)		$	(206,702	)	$	(175,887	)	$	(51,421	)	$	1,676,091	$	33,449
Diluted earnings (loss) per common share		$	(9.71	)	$	(8.26	)	$	(2.41	)	$	78.66	$	1.31



		Predecessor
Year Ended	December 31, 2015	March 31			June 30			September 30			December 31
					(a)			(a)			(a)
		(In thousands, except per share data)

Revenues		$	677,005		$	644,462		$	688,544		$	563,249
Gross profit (loss)		$	14,256		$	(16,507	)	$	47,275		$	(44,964	)
Asset impairment and mine closure costs		$	—		$	19,146		$	2,120,292		$	488,865
Loss from operations		$	(19,712	)	$	(69,546	)	$	(2,236,772	)	$	(539,033	)
Net loss		$	(113,195	)	$	(168,103	)	$	(1,999,476	)	$	(632,368	)
Diluted loss per common share		$	(5.32	)	$	(7.93	)	$	(93.91	)	$	(29.70	)

(b) The Company filed for bankruptcy on January 11, 2016 and subsequently emerged on October 5, 2016. See further discussion in Note 3, “Emergence from Bankruptcy and Fresh Start Accounting.”

Accounting Policies (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Statutory Accounting Practices
Mineral rights	$ 400,000	$ 2,400,000
Deferred finance costs, net	5,182	66,300
Deferred finance costs, current	$ 1,900	$ 65,600
Exploration and Production Equipment [Member] \| Minimum [Member]
Statutory Accounting Practices
Estimated useful life	7 years
Exploration and Production Equipment [Member] \| Maximum [Member]
Statutory Accounting Practices
Estimated useful life	18 years
Building and Building Improvements [Member] \| Minimum [Member]
Statutory Accounting Practices
Estimated useful life	1 year
Building and Building Improvements [Member] \| Maximum [Member]
Statutory Accounting Practices
Estimated useful life	18 years
Mining Properties and Mineral Rights [Member] \| Minimum [Member]
Statutory Accounting Practices
Term of contract	10 years
Mining Properties and Mineral Rights [Member] \| Maximum [Member]
Statutory Accounting Practices
Term of contract	50 years

Accounting Policies (Accounting Principle Adopted) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other current assets		$ 39,866
Revision of debt issuance costs	$ (5,182)	(66,300)
Current maturities of debt		5,042,353
Scenario, Previously Reported [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other current assets		104,723
Current maturities of debt		5,107,210
Accounting Standards Update 03-2015 [Member] \| Other Current Assets [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revision of debt issuance costs		(64,857)
Accounting Standards Update 03-2015 [Member] \| Long-term Debt, Current [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revision of debt issuance costs		$ (64,857)

(Treatment of Claims and New First Lien Debt Facility) (Details)	Oct. 05, 2016 USD ($) $ / shares
Fresh-Start Adjustment [Line Items]
Holders of allowed claims pro-rata amount of cash to settle claims	$ 144,800,000.0
Holders of allowed claims amount of cash to settle claims	$ 30,000,000
Holders of allowed claims percentage of common stock outstanding upon reorganization	94.00%
Holders of allowed claims warrant exercise period	7 years
Holders of allowed claims total equity value of common stock	$ 1,425,000,000
Exercise price of warrants (in usd per share) \| $ / shares	$ 57
Holders of allowed claims percentage of common stock outstanding pursuant to incentive plan upon reorganization	10.00%
Unsecured note holders pro rata amount of cash to settle claims	$ 22,636,000
Unsecured note holders pro rata amount of cash in lieu of warrants	$ 25,000,000
Unsecured note holders percentage of common stock outstanding upon reorganization	6.00%
Other general holders pro rata amount of cash to settle claims	$ 7,364,000
Other general holders professional expenses retained by claims committee	200,000
New First Lien Debt Facility [Member] \| Senior Notes [Member]
Fresh-Start Adjustment [Line Items]
Amount of debt instrument	$ 326,500,000.0
Class A Common Stock [Member]
Fresh-Start Adjustment [Line Items]
Holders of allowed claims percentage of common stock outstanding upon reorganization	12.00%

(Securitization Facility and Warrant Agreement) (Details) - USD ($)	Oct. 05, 2016	Oct. 02, 2016
Fresh-Start Adjustment [Line Items]
Number of securities called by each warrant (in shares)	1
Exercise price of warrants (in usd per share)	$ 57
Percentage of listed common stock	90.00%
Number of shares of common stock underlying warrant multiplier	$ 0
Class A Common Stock [Member]
Fresh-Start Adjustment [Line Items]
Aggregate number of securities called by warrants (in shares)	1,914,856	1,914,856
Common stock, par value (in usd per share)	$ 0.01

(Termination of Material Definitive Agreements, Sale of Equity Securities and Reorganization Value) (Details) - USD ($)	Oct. 05, 2016	Dec. 31, 2016	Oct. 02, 2016	Oct. 01, 2016	Jan. 11, 2016
Fresh-Start Adjustment [Line Items]
Reorganization value			$ 687,500,000
Excess cash			64,000,000
Minimum cash balance assumption			$ 250,000,000
Minimum [Member]
Fresh-Start Adjustment [Line Items]
Reorganization value				$ 650,000,000
Maximum [Member]
Fresh-Start Adjustment [Line Items]
Reorganization value				$ 950,000,000
Discounted Cash Flow Valuation Technique [Member] \| Minimum [Member]
Fresh-Start Adjustment [Line Items]
Discount rate (percent)	13.25%
Discounted Cash Flow Valuation Technique [Member] \| Maximum [Member]
Fresh-Start Adjustment [Line Items]
Discount rate (percent)	15.25%
7.00% Senior Notes Due 2019 [Member]
Fresh-Start Adjustment [Line Items]
Senior notes interest rate (percent)		7.00%			7.00%
7.25% Senior Notes Due 2020 [Member]
Fresh-Start Adjustment [Line Items]
Senior notes interest rate (percent)		7.25%			7.25%
7.25% Senior Notes Due 2021 [Member]
Fresh-Start Adjustment [Line Items]
Senior notes interest rate (percent)		7.25%			7.25%
9.875% Senior Notes Due 2019 [Member]
Fresh-Start Adjustment [Line Items]
Senior notes interest rate (percent)		9.875%			9.875%
Amount of debt instrument		$ 375,000,000
8.00% Senior Secured Notes due 2019 [Member]
Fresh-Start Adjustment [Line Items]
Senior notes interest rate (percent)		8.00%			8.00%
Class A Common Stock [Member]
Fresh-Start Adjustment [Line Items]
Common stock, shares issued (in shares)			24,589,834
Common stock, par value (in usd per share)	$ 0.01
Aggregate number of securities called by warrants (in shares)	1,914,856		1,914,856
Class B Common Stock [Member]
Fresh-Start Adjustment [Line Items]
Common stock, shares issued (in shares)			410,166
Common stock, par value (in usd per share)			$ 0.01
New First Lien Debt Facility [Member] \| Senior Notes [Member]
Fresh-Start Adjustment [Line Items]
Amount of debt instrument	$ 326,500,000.0

Emergence from Bankruptcy and Fresh Start Accounting (Accounting Impact of Emergence) (Details) $ in Thousands	Oct. 01, 2016 USD ($)
Reorganizations [Abstract]
Percentage of voting shares received upon emergence of new entity (percent)	50.00%
Assets
Fresh-Start Adjustment, Increase (Decrease), Property and Equipment, Net	$ (2,363,829)
Fresh Start Adjustments [Member]
Assets
Fresh-Start Adjustment, Increase (Decrease), Receivables, Net	779
Fresh-Start Adjustment, Increase (Decrease), Inventories	(21,078)
Fresh-Start Adjustment, Increase (Decrease), Prepaid and Other Current Assets	53,851
Fresh-Start Adjustment, Increase (Decrease), Current Assets	33,552
Fresh-Start Adjustment, Increase (Decrease), Property and Equipment, Net	(2,363,829)
Fresh-Start Adjustment, Increase (Decrease), Prepaid Royalties	(20,997)
Fresh-Start Adjustment, Increase (Decrease), Equity Investments	(61,606)
Fresh-Start Adjustment, Increase (Decrease), Other Assets, Noncurrent	37,503
Fresh-Start Adjustment, Increase (Decrease), Other Assets	(45,100)
Fresh-Start Adjustment, Increase (Decrease), Assets	(2,375,377)
Liabilities not subject to compromise
Fresh-Start Adjustment, Increase (Decrease), Accounts Payable	(250)
Fresh-Start Adjustment, Increase (Decrease), Accrued Liabilities and Other Current Liabilities	26,644
Fresh-Start Adjustment, Increase (Decrease), Current Liabilities	26,394
Fresh-Start Adjustment, Increase (Decrease), Asset Retirement Obligations	(60,570)
Fresh-Start Adjustment, Increase (Decrease), Pension Obligations	24,565
Fresh-Start Adjustment, Increase (Decrease), Other Postretirement Obligations	24,836
Fresh-Start Adjustment, Increase (Decrease), Accrued Workers' Compensation	74,520
Fresh-Start Adjustment, Increase (Decrease), Noncurrent Other Obligations	888
Fresh-Start Adjustment, Increase (Decrease), Other Noncurrent Obligations	90,633
Fresh-Start Adjustment, Increase (Decrease), Liabilities	90,633
Stockholders’ equity (deficit)
Fresh-Start Adjustment, Increase (Decrease), Retained Earnings (Deficit)	(2,467,716)
Fresh-Start Adjustment, Increase (Decrease), Accumulated Other Comprehensive Income (Loss)	1,706
Fresh-Start Adjustment, Increase (Decrease), Stockholders' Equity	(2,466,010)
Fresh-Start Adjustment, Increase (Decrease), Liabilities and Stockholders' Equity	(2,375,377)
Effect of Plan [Member]
Assets
Fresh-Start Adjustment, Increase (Decrease), Cash and Cash Equivalents	(199,718)
Fresh-Start Adjustment, Increase (Decrease), Prepaid and Other Current Assets	6,367
Fresh-Start Adjustment, Increase (Decrease), Current Assets	(193,351)
Fresh-Start Adjustment, Increase (Decrease), Other Assets, Noncurrent	34,495
Fresh-Start Adjustment, Increase (Decrease), Other Assets	34,495
Fresh-Start Adjustment, Increase (Decrease), Assets	(158,856)
Liabilities not subject to compromise
Fresh-Start Adjustment, Increase (Decrease), Accrued Liabilities and Other Current Liabilities	(36,331)
Fresh-Start Adjustment, Increase (Decrease), Current Maturities of Long-term Debt	3,265
Fresh-Start Adjustment, Increase (Decrease), Current Liabilities	(33,066)
Fresh-Start Adjustment, Increase (Decrease), Long-term Debt	323,235
Fresh-Start Adjustment, Increase (Decrease), Other Noncurrent Obligations	290,169
Fresh-Start Adjustment, Increase (Decrease), Liabilities Subject to Compromise	(5,278,612)
Fresh-Start Adjustment, Increase (Decrease), Liabilities	(4,988,443)
Stockholders’ equity (deficit)
Fresh-Start Adjustment, Increase (Decrease), Preferred and Common Stock Held in Treasury	53,863
Fresh-Start Adjustment, Increase (Decrease), Retained Earnings (Deficit)	7,146,693
Fresh-Start Adjustment, Increase (Decrease), Stockholders' Equity	4,829,587
Fresh-Start Adjustment, Increase (Decrease), Liabilities and Stockholders' Equity	(158,856)
Predecessor [Member]
Preconfirmation
Preconfirmation, Cash and cash equivalents	400,205
Preconfirmation, Short term investments	111,451
Preconfirmation, Restricted cash	81,563
Preconfirmation, Trade accounts receivable	165,522
Preconfirmation, Other Receivables	17,227
Preconfirmation, Inventories	159,410
Preconfirmation, Prepaid Royalties, Current	4,805
Preconfirmation, Deferred Income Tax Assets, Current	0
Preconfirmation, Coal Derivative Assets	2,180
Preconfirmation, Prepaid and Other Current Assets	36,960
Preconfirmation, Current Assets	979,323
Preconfirmation, Property and Equipment, Net	3,434,941
Preconfirmation, Prepaid Royalties, Noncurrent	20,997
Preconfirmation, Investments	164,232
Preconfirmation, Other Assets, Noncurrent	58,569
Preconfirmation, Other Assets	243,798
Preconfirmation, Assets	4,658,062
Preconfirmation, Accounts Payable	74,595
Precomfirmation, Accrued expenses and other current liabilities	225,739
Preconfirmation, Current Maturities of Long-term Debt	3,397
Preconfirmation, Current Liabilities	303,731
Preconfirmation, Long-term Debt	30,037
Preconfirmation, Asset Retirement Obligations	394,699
Preconfirmation, Pension Obligations	23,716
Preconfirmation, Other Postretirement Obligations	87,123
Preconfirmation, Accrued Workers' Compensation	119,828
Preconfirmation, Noncurrent Other Obligations	96,410
Preconfirmation, Liabilities Not Subject to Compromise	1,055,544
Preconfirmation, Liabilities Subject to Compromise	5,278,612
Preconfirmation, Liabilities	6,334,156
Preconfirmation, Common Stock	2,145
Preconfirmation, Additional Paid-in Capital	3,056,307
Preconfirmation, Preferred and Common Stock Held in Treasury	(53,863)
Preconfirmation, Retained Earnings (Deficit)	(4,678,977)
Preconfirmation, Accumulated Other Comprehensive Income (Loss)	(1,706)
Preconfirmation, Stockholders' Equity	(1,676,094)
Preconfirmation, Liabilities and Stockholders' Equity	4,658,062
Stockholders’ equity (deficit)
Fresh-Start Adjustment, Increase (Decrease), Common Stock	(2,145)
Fresh-Start Adjustment, Increase (Decrease), Additional Paid-in Capital	(3,056,307)
Fresh-Start Adjustment, Increase (Decrease), Preferred and Common Stock Held in Treasury	53,863
Fresh-Start Adjustment, Increase (Decrease), Retained Earnings (Deficit)	7,146,693
Predecessor [Member] \| Effect of Plan [Member]
Stockholders’ equity (deficit)
Fresh-Start Adjustment, Increase (Decrease), Common Stock	(2,145)
Fresh-Start Adjustment, Increase (Decrease), Additional Paid-in Capital	(3,056,307)
Successor [Member]
Postconfirmation
Postconfirmation, Cash and Cash Equivalents	200,487
Postconfirmation, Short-term Investments	111,451
Postconfirmation, Restricted Cash and Cash Equivalents, Current	81,563
Postconfirmation, Receivables, Net	165,522
Postconfirmation, Other Receivables	18,006
Postconfirmation, Inventories	138,332
Postconfirmation, Prepaid Royalties, Current	4,805
Postconfirmation, Deferred Income Tax Assets, Current	0
Postconfirmation, Coal Derivative Assets	2,180
Postconfirmation, Prepaid and Other Current Assets	97,178
Postconfirmation, Current Assets	819,524
Postconfirmation, Property and Equipment, Net	1,071,112
Postconfirmation, Prepaid Royalties, Noncurrent	0
Postconfirmation, Investments	102,626
Postconfirmation, Other Assets, Noncurrent	130,567
Postconfirmation, Other Assets	233,193
Postconfirmation, Assets	2,123,829
Postconfirmation, Accounts Payable	74,345
Postcomfirmation, Accrued expenses and other current liabilities	216,052
Postconfirmation, Current Maturities of Long-term Debt	6,662
Postconfirmation, Current Liabilities	297,059
Postconfirmation, Long-term Debt	353,272
Postconfirmation, Asset Retirement Obligations	334,129
Postconfirmation, Pension Obligations	48,281
Postconfirmation, Other Postretirement Obligations	111,959
Postconfirmation, Accrued Workers' Compensation	194,348
Postconfirmation, Noncurrent Other Obligations	97,298
Postconfirmation, Liabilities Not Subject to Compromise	1,436,346
Postconfirmation, Liabilities Subject to Compromise	0
Postconfirmation, Liabilities	1,436,346
Postconfirmation, Common Stock	250
Postconfirmation, Additional Paid-in Capital	687,233
Postconfirmation, Preferred and Common Stock Held in Treasury	0
Postconfirmation, Retained Earnings (Deficit)	0
Postconfirmation, Accumulated Other Comprehensive Income (Loss)	0
Postconfirmation, Stockholders' Equity	687,483
Postconfirmation, Liabilities and Stockholders' Equity	2,123,829
Successor [Member] \| Effect of Plan [Member]
Stockholders’ equity (deficit)
Fresh-Start Adjustment, Increase (Decrease), Common Stock	250
Fresh-Start Adjustment, Increase (Decrease), Additional Paid-in Capital	$ 687,233

Emergence from Bankruptcy and Fresh Start Accounting (Liabilities Subject to Compromise) (Details) $ in Thousands	Oct. 01, 2016 USD ($)
Reorganizations [Abstract]
Liabilities subject to compromise	$ 5,278,612
Common stock (at par) Successor	(250)
Warrants Successor	(14,822)
Paid-in capital Successor	(672,411)
Issuance of Term Loan Successor	(326,500)
Cash payment to settle claims and professional fees	(122,525)
Total pre-tax gain on plan effects	$ 4,142,104

Emergence from Bankruptcy and Fresh Start Accounting (Cash Used) (Details) $ in Thousands	Oct. 05, 2016 USD ($)
Reorganizations [Abstract]
Payment to secured lenders	$ 43,496
Payments to unsecured creditors	42,399
Final adequate protection payment	36,331
Collateral requirements	31,665
Professional fees	31,630
Other	14,197
Total cash outflow at emergence	$ 199,718

Emergence from Bankruptcy and Fresh Start Accounting (Reorganization Adjustments and Property, Plant and Equipment) (Details) - USD ($) $ in Thousands		3 Months Ended	9 Months Ended	12 Months Ended
	Oct. 01, 2016	Dec. 31, 2016	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
Fresh-Start Adjustment [Line Items]
Fresh-Start Adjustment, Increase (Decrease), Property and Equipment, Net	$ (2,363,829)		$ (2,363,829)
Total pre-tax gain on plan effects	4,142,104
Coal Properties, Net [Member]
Fresh-Start Adjustment [Line Items]
Fresh-Start Adjustment, Increase (Decrease), Property and Equipment, Net	(1,971,314)		(1,971,314)
Plant and Equipment, Net [Member]
Fresh-Start Adjustment [Line Items]
Fresh-Start Adjustment, Increase (Decrease), Property and Equipment, Net	(405,259)		(405,259)
Deferred Charges, Net [Member]
Fresh-Start Adjustment [Line Items]
Fresh-Start Adjustment, Increase (Decrease), Property and Equipment, Net	12,744		12,744
Predecessor [Member]
Fresh-Start Adjustment [Line Items]
Property, plant and equipment, net	3,434,941		3,434,941	$ 3,619,029
Total pre-tax gain on plan effects	4,142,104		4,142,104	$ 0	$ 0
Cancellation of predecessor common stock	2,145		2,145
Cancellation of predecessor paid-in capital	3,056,307		3,056,307
Cancellation of predecessor treasury stock	(53,863)		(53,863)
Net impact on accumulated earnings (deficit)	7,146,693		7,146,693
Predecessor [Member] \| Coal Properties, Net [Member]
Fresh-Start Adjustment [Line Items]
Property, plant and equipment, net	2,358,779		2,358,779
Predecessor [Member] \| Plant and Equipment, Net [Member]
Fresh-Start Adjustment [Line Items]
Property, plant and equipment, net	812,888		812,888
Predecessor [Member] \| Deferred Charges, Net [Member]
Fresh-Start Adjustment [Line Items]
Property, plant and equipment, net	263,274		263,274
Successor [Member]
Fresh-Start Adjustment [Line Items]
Property, plant and equipment, net	1,071,112	$ 1,053,603	1,071,112
Total pre-tax gain on plan effects		$ 0
Successor [Member] \| Coal Properties, Net [Member]
Fresh-Start Adjustment [Line Items]
Property, plant and equipment, net	387,465		387,465
Successor [Member] \| Plant and Equipment, Net [Member]
Fresh-Start Adjustment [Line Items]
Property, plant and equipment, net	407,629		407,629
Successor [Member] \| Deferred Charges, Net [Member]
Fresh-Start Adjustment [Line Items]
Property, plant and equipment, net	$ 276,018		$ 276,018

Emergence from Bankruptcy and Fresh Start Accounting (Unsecured or Under-Secured Liabilities Previously Reported) (Details) - USD ($) $ in Thousands	Oct. 01, 2016	Jan. 11, 2016
Fresh-Start Adjustment [Line Items]
Liabilities Subject to Compromise	$ 5,278,612
Scenario, Previously Reported [Member]
Fresh-Start Adjustment [Line Items]
Debt		$ 5,026,806
Accrued expenses and other current liabilities		136,295
Accounts payable		106,297
Other noncurrent liabilities		9,214
Liabilities Subject to Compromise		$ 5,278,612

Emergence from Bankruptcy and Fresh Start Accounting (Additional Information to Liabilities Subject to Compromise) (Details) - USD ($) $ in Thousands	Oct. 05, 2016	Oct. 01, 2016	Dec. 31, 2016	Dec. 31, 2015
Fresh-Start Adjustment [Line Items]
Fair value of senior notes and other long-term debt, including amounts classified as current			$ 362,900	$ 937,100
Current maturities of debt				$ 5,042,353
Insurance receivable, current			800
Decrease in property plant and equipment, net		$ 2,363,829
Successor [Member]
Fresh-Start Adjustment [Line Items]
Current maturities of debt			11,038
Term Loan Due 2021 [Member]
Fresh-Start Adjustment [Line Items]
Term loan			325,684
Term Loan Due 2021 [Member] \| Successor [Member]
Fresh-Start Adjustment [Line Items]
Fair value of senior notes and other long-term debt, including amounts classified as current		326,500
Term loan			$ 325,684
Current maturities of debt		$ 3,300
Minimum [Member] \| Discounted Cash Flow Valuation Technique [Member]
Fresh-Start Adjustment [Line Items]
Discount rate (percent)	13.25%
Maximum [Member] \| Discounted Cash Flow Valuation Technique [Member]
Fresh-Start Adjustment [Line Items]
Discount rate (percent)	15.25%
Asset Retirement Obligation Costs [Member] \| Minimum [Member] \| Discounted Cash Flow Valuation Technique [Member]
Fresh-Start Adjustment [Line Items]
Discount rate (percent)		7.06%
Asset Retirement Obligation Costs [Member] \| Maximum [Member] \| Discounted Cash Flow Valuation Technique [Member]
Fresh-Start Adjustment [Line Items]
Discount rate (percent)		9.08%
Plant and Equipment, Net [Member]
Fresh-Start Adjustment [Line Items]
Decrease in property plant and equipment, net		$ 405,259
Plant and Equipment, Net [Member] \| Market Approach and Cost Approach Valuation Techniques [Member] \| Successor [Member]
Fresh-Start Adjustment [Line Items]
Fair value of property, plant and equipment, net		407,600
Coal Properties, Net [Member]
Fresh-Start Adjustment [Line Items]
Decrease in property plant and equipment, net		1,971,314
Coal Properties, Net [Member] \| Discounted Cash Flow and Market Approach Valuation Techniques [Member] \| Successor [Member]
Fresh-Start Adjustment [Line Items]
Fair value of property, plant and equipment, net		387,500
Fresh Start Adjustments [Member]
Fresh-Start Adjustment [Line Items]
Increase (decrease) in inventories		(21,078)
Increase in current above market sales contracts		71,100
Decrease in prepaid expenses		11,300
Decrease in property plant and equipment, net		2,363,829
Increase in current below market sales contracts		27,800
Increase in noncurrent above market sales contract		26,000
Increase in noncurrent insurance receivables		18,600
Decrease in noncurrent prepaid balances		13,200
Increase in noncurrent below market sales contracts		3,900
Decrease in miscellaneous noncurrent liabilities		3,100
Fresh Start Adjustments [Member] \| Coal Inventory [Member]
Fresh-Start Adjustment [Line Items]
Increase (decrease) in inventories		7,300
Fresh Start Adjustments [Member] \| Critical Spare Parts [Member]
Fresh-Start Adjustment [Line Items]
Increase (decrease) in inventories		$ (28,400)
Equity Method Investments [Member] \| Level 3 [Member] \| Discounted Cash Flow Approach and Comparable Company Approach [Member]
Fresh-Start Adjustment [Line Items]
Discount rate (percent)		14.00%

Emergence from Bankruptcy and Fresh Start Accounting (Reorganization Items, Net and Contractual Interest Expense During Bankruptcy) (Details) - USD ($) $ in Thousands		3 Months Ended				9 Months Ended	12 Months Ended
	Oct. 01, 2016	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
Fresh-Start Adjustment [Line Items]
Gain on settlement of claims	$ 4,142,104
Predecessor [Member]
Fresh-Start Adjustment [Line Items]
Gain on settlement of claims	4,142,104					$ 4,142,104	$ 0	$ 0
Fresh start adjustments						(2,466,010)	0	0
Professional fees						(46,053)	0	0
Reorganization Items	$ 1,676,091		$ (20,904)	$ (21,271)	$ (3,875)	1,630,041	$ 0	$ 0
Contractual interest expense						300,900
Interest Expense						$ 135,900
Successor [Member]
Fresh-Start Adjustment [Line Items]
Gain on settlement of claims		$ 0
Fresh start adjustments		0
Professional fees		(759)
Reorganization Items		$ (759)

Accumulated Other Comprehensive Income (Loss) (Schedule of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2016	Oct. 01, 2016	Dec. 31, 2015
Predecessor [Member]
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]
Beginning balance		$ (1,815)
Unrealized gains (losses)		563	$ (8,153)
Amounts reclassified from accumulated other comprehensive income (loss)		(454)	3,097
Fresh start accounting adjustment		1,706
Ending balance			(1,815)
Predecessor [Member] \| Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]
Beginning balance	$ 0	(1,815)	3,241
Ending balance		0	(1,815)
Predecessor [Member] \| Derivative Instruments [Member]
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]
Beginning balance	0	325	2,550
Unrealized gains (losses)		(138)	3,903
Amounts reclassified from accumulated other comprehensive income (loss)		(316)	(6,128)
Fresh start accounting adjustment		129
Ending balance		0	325
Predecessor [Member] \| Pension, Postretirement and Other Post-Employment Benefits [Member]
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]
Beginning balance	0	(721)	2,860
Unrealized gains (losses)		0	(8,723)
Amounts reclassified from accumulated other comprehensive income (loss)		(1,363)	5,142
Fresh start accounting adjustment		2,084
Ending balance		0	(721)
Predecessor [Member] \| Available-for-Sale Securities [Member]
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]
Beginning balance	0	(1,419)	(2,169)
Unrealized gains (losses)		701	(3,333)
Amounts reclassified from accumulated other comprehensive income (loss)		1,225	4,083
Fresh start accounting adjustment		(507)
Ending balance		$ 0	$ (1,419)
Successor [Member]
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]
Unrealized gains (losses)	24,454
Amounts reclassified from accumulated other comprehensive income (loss)	0
Ending balance	24,454
Successor [Member] \| Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]
Ending balance	24,454
Successor [Member] \| Derivative Instruments [Member]
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]
Unrealized gains (losses)	0
Amounts reclassified from accumulated other comprehensive income (loss)	0
Ending balance	0
Successor [Member] \| Pension, Postretirement and Other Post-Employment Benefits [Member]
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]
Unrealized gains (losses)	24,067
Amounts reclassified from accumulated other comprehensive income (loss)	0
Ending balance	24,067
Successor [Member] \| Available-for-Sale Securities [Member]
Accumulated Other Comprenhensive Income (Loss) [Roll Forward]
Unrealized gains (losses)	387
Amounts reclassified from accumulated other comprehensive income (loss)	0
Ending balance	$ 387

Accumulated Other Comprehensive Income (Loss) (Schedule of Reclassifications) (Details) - USD ($) $ in Thousands		3 Months Ended								9 Months Ended	12 Months Ended
	Oct. 01, 2016	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
Successor [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Revenues		$ 575,688
Income (loss) before income taxes		34,605
Provision for (benefit from) income taxes		(1,156)
Net income (loss)		33,449
Successor [Member] \| Reclassification out of accumulated other comprehensive income [Member] \| Derivative Instruments [Member] \| Commodity Contract [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Revenues		0
Provision for (benefit from) income taxes		0
Net income (loss)		0
Successor [Member] \| Reclassification out of accumulated other comprehensive income [Member] \| Pension, Postretirement and Other Post-Employment Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amortization of prior service credits		0
Amortization of net actuarial gains (losses)		0
Income (loss) before income taxes		0
Provision for (benefit from) income taxes		0
Net income (loss)		0
Successor [Member] \| Reclassification out of accumulated other comprehensive income [Member] \| Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest and investment income		0
Provision for (benefit from) income taxes		0
Net income (loss)		$ 0
Predecessor [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Revenues			$ 550,305	$ 420,298	$ 428,106	$ 563,249	$ 688,544	$ 644,462	$ 677,005	$ 1,398,709	$ 2,573,260	$ 2,937,119
Income (loss) before income taxes										1,237,455	(3,286,522)	(532,719)
Provision for (benefit from) income taxes										4,626	373,380	(25,634)
Net income (loss)	$ 1,676,091		$ (51,421)	$ (175,887)	$ (206,702)	$ (632,368)	$ (1,999,476)	$ (168,103)	$ (113,195)	1,242,081	(2,913,142)	$ (558,353)
Predecessor [Member] \| Reclassification out of accumulated other comprehensive income [Member] \| Derivative Instruments [Member] \| Commodity Contract [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Revenues										397	9,575
Provision for (benefit from) income taxes										(81)	(3,447)
Net income (loss)										316	6,128
Predecessor [Member] \| Reclassification out of accumulated other comprehensive income [Member] \| Pension, Postretirement and Other Post-Employment Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amortization of prior service credits										7,854	8,335
Amortization of net actuarial gains (losses)										(6,010)	(16,369)
Income (loss) before income taxes										1,844	(8,034)
Provision for (benefit from) income taxes										(481)	2,892
Net income (loss)										1,363	(5,142)
Predecessor [Member] \| Reclassification out of accumulated other comprehensive income [Member] \| Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest and investment income										(2,263)	(6,391)
Provision for (benefit from) income taxes										1,038	2,308
Net income (loss)										$ (1,225)	$ (4,083)

Impairment Charges and Mine Closure Costs (Details) - USD ($) $ in Millions	3 Months Ended						6 Months Ended		12 Months Ended
	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2016	Dec. 31, 2015	Dec. 31, 2015
Impaired Long-Lived Assets Held and Used [Line Items]
Other-than-temporary impairment loss on available-for-sale securities		$ 2.9
Severance costs							$ 7.2
Curtailments							$ 3.6
Asset impairment and mine closure costs			$ 488.9	$ 2,100.0	$ 19.1			$ 2,600.0
Impairment charge of higher-cost mining complex					5.6
Restructuring charges				$ 5.1
Royalty Agreements [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Prepaid royalties		3.4			$ 12.2
Impairment charge						$ 15.4			$ 48.0
APP [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment and mine closure costs									2,200.0
Other Segments [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment and mine closure costs									$ 400.0
Kentucky [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Net book value of idled facility		$ 74.1
Longview, Washington [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Other-than-temporary impairment loss on available-for-sale securities	$ 38.0

Impairment Charges and Mine Closure Costs (Summary Asset Impairments and Mine Closure Costs) (Details) - USD ($) $ in Thousands	3 Months Ended								6 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2015	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment and mine closure costs					$ 488,900	$ 2,100,000	$ 19,100		$ 2,600,000
Predecessor [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Coal lands and mineral rights										$ 74,144	$ 2,210,488	$ 0
Plant and equipment										0	199,107	1,512
Deferred development										0	159,474	0
Prepaid royalties										3,406	41,990	15,356
Equity investments										40,920	21,325	0
Inventories										0	66	0
Other										10,797	(4,147)	7,245
Asset impairment and mine closure costs		$ 46	$ 43,701	$ 85,520	$ 488,865	$ 2,120,292	$ 19,146	$ 0		$ 129,267	$ 2,628,303	$ 24,113
Successor [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Coal lands and mineral rights	$ 0
Plant and equipment	0
Deferred development	0
Prepaid royalties	0
Equity investments	0
Inventories	0
Other	0
Asset impairment and mine closure costs	$ 0

Losses from disposed operations resulting from Patriot Coal Bankruptcy (Details) - Magnum [Member] - USD ($) $ in Millions		12 Months Ended
	Nov. 22, 2016	Dec. 31, 2015
Discontinued Operations, Held-for-sale or Disposed of by Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Losses related to previously disposed off operations		$ 116.3
Surety Bond [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Decease in collateral held by bonding company	$ 20.0

Inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Allowance for slow-moving and obsolete inventories	$ 0	$ 6,000
Successor [Member]
Property, Plant and Equipment [Line Items]
Coal	37,268
Repair parts and supplies	76,194
Inventories	$ 113,462
Predecessor [Member]
Property, Plant and Equipment [Line Items]
Coal		85,043
Repair parts and supplies		111,677
Inventories		$ 196,720

Investments in Available-for-Sale Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Successor [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost Basis	$ 89,910
Gross Unrealized Gains	388
Gross Unrealized Losses	(89)
Fair Value	90,209
Total Investments	88,072
Successor [Member] \| Short-term Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Corporate notes and bonds	88,072
Total Investments	88,072
Successor [Member] \| Other Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Equity Securities, Fair Value	2,137
Successor [Member] \| Corporate Notes and Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Debt Securities, Amortized Cost Basis	88,161
Debt Securities, Gross Unrealized Gains	0
Debt Securities, Gross Unrealized Losses	(89)
Debt Securities, Fair Value	88,072
Successor [Member] \| Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Equity Securities, Amortized Cost Basis	1,749
Equity Securities, Gross Unrealized Gains	388
Equity Securities, Gross Unrealized Losses	0
Equity Securities, Fair Value	$ 2,137
Predecessor [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost Basis		$ 204,441
Gross Unrealized Gains		668
Gross Unrealized Losses		(3,199)
Fair Value		201,910
Total Investments		200,192
Predecessor [Member] \| Short-term Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
US government and agency securities		9,995
Corporate notes and bonds		190,197
Total Investments		200,192
Predecessor [Member] \| Other Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Equity Securities, Fair Value		1,718
Predecessor [Member] \| US Government and Agency Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Debt Securities, Amortized Cost Basis		10,007
Debt Securities, Gross Unrealized Gains		0
Debt Securities, Gross Unrealized Losses		(12)
Debt Securities, Fair Value		9,995
Predecessor [Member] \| Corporate Notes and Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Debt Securities, Amortized Cost Basis		190,496
Debt Securities, Gross Unrealized Gains		0
Debt Securities, Gross Unrealized Losses		(299)
Debt Securities, Fair Value		190,197
Predecessor [Member] \| Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Equity Securities, Amortized Cost Basis		3,938
Equity Securities, Gross Unrealized Gains		668
Equity Securities, Gross Unrealized Losses		(2,888)
Equity Securities, Fair Value		$ 1,718

Investments in Available-for-Sale Securities (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Available-for-sale Securities [Abstract]
Continuous unrealized loss position for less than a year	$ 47.6	$ 184.6
Continuous unrealized loss position for over a year	$ 40.4	$ 15.8

Equity Method Investments and Membership Interests in Joint Ventures (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2016	Sep. 30, 2015	Dec. 31, 2016	Dec. 31, 2015
Knight Hawk [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest (percent)			49.00%
DTA [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest (percent)				21.875%
Millennium [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest (percent)				38.00%
Impairment of equity investment	$ (38,000)
Tongue River [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest (percent)				35.00%
Impairment of equity investment		$ (21,300)

Equity Method Investments and Membership Interests in Joint Ventures (Schedule of Equity Method Investments) (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended	12 Months Ended
	Dec. 31, 2016	Jun. 30, 2016	Sep. 30, 2015	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
Millennium [Member]
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Impairment of equity investment		$ (38,000)
Tongue River [Member]
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Impairment of equity investment			$ (21,300)
Predecessor [Member]
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Beginning Balance	$ 102,625			$ 201,877	$ 235,842	$ 221,456
Advances to (distributions from) affiliates, net				(4,934)	(18,360)	4,054
Equity in comprehensive income (loss)				5,314	7,979	10,332
Impairment of equity investment				(38,025)	(21,325)
Sale of equity investment					(2,259)
Fresh start accounting adjustment				(61,607)
Ending Balance				102,625	201,877	235,842
Predecessor [Member] \| Knight Hawk [Member]
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Beginning Balance	94,000			151,592	158,477	152,806
Advances to (distributions from) affiliates, net				(8,374)	(29,862)	(12,603)
Equity in comprehensive income (loss)				9,033	22,977	18,274
Impairment of equity investment				0
Fresh start accounting adjustment				(58,251)
Ending Balance				94,000	151,592	158,477
Predecessor [Member] \| DTA [Member]
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Beginning Balance	8,600			13,239	13,738	14,137
Advances to (distributions from) affiliates, net				1,474	3,207	3,774
Equity in comprehensive income (loss)				(2,095)	(3,706)	(4,173)
Fresh start accounting adjustment				(4,018)
Ending Balance				8,600	13,239	13,738
Predecessor [Member] \| Millennium [Member]
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Beginning Balance	0			37,589	40,223	35,894
Advances to (distributions from) affiliates, net				1,966	7,052	6,742
Equity in comprehensive income (loss)				(1,530)	(9,686)	(2,413)
Impairment of equity investment				(38,025)
Fresh start accounting adjustment				0
Ending Balance				0	37,589	40,223
Predecessor [Member] \| Tongue River [Member]
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Beginning Balance	0				20,740	18,419
Advances to (distributions from) affiliates, net				0	913	2,541
Equity in comprehensive income (loss)				0	(328)	(220)
Impairment of equity investment				0	(21,325)
Fresh start accounting adjustment				0
Ending Balance				0		20,740
Predecessor [Member] \| Other [Member]
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Beginning Balance	25			(543)	2,664	200
Advances to (distributions from) affiliates, net				0	330	3,600
Equity in comprehensive income (loss)				(94)	(1,278)	(1,136)
Impairment of equity investment				0
Sale of equity investment					(2,259)
Fresh start accounting adjustment				662
Ending Balance				$ 25	$ (543)	$ 2,664
Successor [Member]
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Advances to (distributions from) affiliates, net	(8,254)
Equity in comprehensive income (loss)	1,703
Ending Balance	96,074
Successor [Member] \| Knight Hawk [Member]
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Advances to (distributions from) affiliates, net	(9,076)
Equity in comprehensive income (loss)	2,569
Ending Balance	87,493
Successor [Member] \| DTA [Member]
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Advances to (distributions from) affiliates, net	822
Equity in comprehensive income (loss)	(841)
Ending Balance	8,581
Successor [Member] \| Millennium [Member]
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Ending Balance	0
Successor [Member] \| Tongue River [Member]
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Ending Balance	0
Successor [Member] \| Other [Member]
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Equity in comprehensive income (loss)	(25)
Ending Balance	$ 0

Sales Contracts (Narrative) (Details) $ in Millions	Dec. 31, 2016 USD ($)
Acquired Sales Contracts [Abstract]
2017	$ 54.3
2018	10.7
2019	1.1
2020	0.6
2021	$ 0.1

Sales Contracts (Schedule of Sales Contracts) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2016	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
Successor [Member]
Acquired Finite-Lived Intangible Assets And Liabilities By Major Class [Line Items]
Prepaid royalties	$ 0
Acquired fair value, Assets	97,196
Acquired fair value, Liabilities	31,742
Accumulated amortization, Asset	(25,625)
Accumulated amortization, Liabilities	(24,829)
Total, Assets	71,571
Total, Liabilities	6,913
Net total, Liabilities	64,658
Coal Supply Agreement, Liabilities	5,114
Successor [Member] \| Other Current Assets [Member]
Acquired Finite-Lived Intangible Assets And Liabilities By Major Class [Line Items]
Coal supply agreement, Assets	59,702
Successor [Member] \| Accrued Liabilities [Member]
Acquired Finite-Lived Intangible Assets And Liabilities By Major Class [Line Items]
Coal Supply Agreement, Liabilities	5,114
Successor [Member] \| Other Assets [Member]
Acquired Finite-Lived Intangible Assets And Liabilities By Major Class [Line Items]
Coal supply agreement, Assets	11,869
Successor [Member] \| Other Noncurrent Liabilities [Member]
Acquired Finite-Lived Intangible Assets And Liabilities By Major Class [Line Items]
Coal Supply Agreement, Liabilities	$ 1,799
Predecessor [Member]
Acquired Finite-Lived Intangible Assets And Liabilities By Major Class [Line Items]
Prepaid royalties		$ 3,406	$ 41,990	$ 15,356
Acquired fair value, Assets			131,299
Acquired fair value, Liabilities			166,697
Accumulated amortization, Asset			(130,839)
Accumulated amortization, Liabilities			(151,354)
Total, Assets			460
Total, Liabilities			15,343
Net total, Liabilities			(14,883)
Coal Supply Agreement, Liabilities			3,852
Predecessor [Member] \| Other Current Assets [Member]
Acquired Finite-Lived Intangible Assets And Liabilities By Major Class [Line Items]
Coal supply agreement, Assets			460
Predecessor [Member] \| Accrued Liabilities [Member]
Acquired Finite-Lived Intangible Assets And Liabilities By Major Class [Line Items]
Coal Supply Agreement, Liabilities			3,852
Predecessor [Member] \| Other Assets [Member]
Acquired Finite-Lived Intangible Assets And Liabilities By Major Class [Line Items]
Coal supply agreement, Assets			0
Predecessor [Member] \| Other Noncurrent Liabilities [Member]
Acquired Finite-Lived Intangible Assets And Liabilities By Major Class [Line Items]
Coal Supply Agreement, Liabilities			$ 11,491

Derivatives (Narrative) (Details) gal in Millions, $ in Millions	9 Months Ended	12 Months Ended
	Oct. 01, 2016 USD ($)	Dec. 31, 2016 USD ($) gal $ / option	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Derivative [Line Items]
Net unrealized and realized gains (losses) related to trading portfolio	$ (0.9)		$ 5.7	$ 3.2
Year One [Member]
Derivative [Line Items]
Value of trading portfolio realized		$ 0.2
Diesel Purchases [Member] \| Heating Oil [Member]
Derivative [Line Items]
Quantities under derivative contracts \| gal		30.7
Average strike price (in dollars per option) \| $ / option		1.72
Diesel Purchases [Member] \| Minimum [Member]
Derivative [Line Items]
Gallons of diesel fuel purchased annually \| gal		45.0
Diesel Purchases [Member] \| Maximum [Member]
Derivative [Line Items]
Gallons of diesel fuel purchased annually \| gal		50.0
Other Current Liabilities [Member]
Derivative [Line Items]
Right to reclaim cash collateral, liability			$ 1.7
Other Current Assets [Member]
Derivative [Line Items]
Right to reclaim cash collateral, asset		$ 2.8

Derivatives (Schedule of Price Risk Derivatives) (Details) T in Thousands	Dec. 31, 2016 T
Coal Sales [Member]
Derivative [Line Items]
Derivatives Held	540
Coal Purchases [Member]
Derivative [Line Items]
Derivatives Held	480
Year One [Member] \| Coal Sales [Member]
Derivative [Line Items]
Derivatives Held	540
Year One [Member] \| Coal Purchases [Member]
Derivative [Line Items]
Derivatives Held	480
Year Two [Member] \| Coal Sales [Member]
Derivative [Line Items]
Derivatives Held	0
Year Two [Member] \| Coal Purchases [Member]
Derivative [Line Items]
Derivatives Held	0

Derivatives (Disclosure of Fair Value of Derivatives) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Predecessor [Member]
Derivative [Line Items]
Derivative Assets		$ 116,080
Derivative Liabilities		(107,028)
Effect of counterparty netting in derivative assets		(107,028)
Effect of counterparty netting in derivative liabilities		107,028
Net derivative assets as classified in the balance sheet		9,052
Net derivative liabilities as classified in the balance sheet		0
Net derivatives as classified in the balance sheet		9,052
Predecessor [Member] \| Designated as Hedging Instrument [Member] \| Coal [Member]
Derivative [Line Items]
Derivative Assets		4
Derivative Liabilities		(20)
Predecessor [Member] \| Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Assets		116,076
Derivative Liabilities		(107,008)
Predecessor [Member] \| Not Designated as Hedging Instrument [Member] \| Heating Oil-Diesel Purchases [Member]
Derivative [Line Items]
Derivative Assets		1,017
Predecessor [Member] \| Not Designated as Hedging Instrument [Member] \| Coal Held for Trading Purposes [Member]
Derivative [Line Items]
Derivative Assets		110,653
Derivative Liabilities		(104,814)
Predecessor [Member] \| Not Designated as Hedging Instrument [Member] \| Coal [Member]
Derivative [Line Items]
Derivative Assets		3,912
Derivative Liabilities		(1,947)
Predecessor [Member] \| Not Designated as Hedging Instrument [Member] \| Natural Gas [Member]
Derivative [Line Items]
Derivative Assets		494
Derivative Liabilities		$ (247)
Successor [Member]
Derivative [Line Items]
Derivative Assets	$ 74,155
Derivative Liabilities	(69,348)
Effect of counterparty netting in derivative assets	(69,247)
Effect of counterparty netting in derivative liabilities	69,247
Net derivative assets as classified in the balance sheet	4,908
Net derivative liabilities as classified in the balance sheet	(101)
Net derivatives as classified in the balance sheet	4,807
Successor [Member] \| Designated as Hedging Instrument [Member] \| Coal [Member]
Derivative [Line Items]
Derivative Assets	0
Derivative Liabilities	(15)
Successor [Member] \| Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Assets	74,155
Derivative Liabilities	(69,333)
Successor [Member] \| Not Designated as Hedging Instrument [Member] \| Heating Oil-Diesel Purchases [Member]
Derivative [Line Items]
Derivative Assets	4,646
Successor [Member] \| Not Designated as Hedging Instrument [Member] \| Coal Held for Trading Purposes [Member]
Derivative [Line Items]
Derivative Assets	68,948
Derivative Liabilities	(68,740)
Successor [Member] \| Not Designated as Hedging Instrument [Member] \| Coal [Member]
Derivative [Line Items]
Derivative Assets	475
Derivative Liabilities	(580)
Successor [Member] \| Not Designated as Hedging Instrument [Member] \| Natural Gas [Member]
Derivative [Line Items]
Derivative Assets	86
Derivative Liabilities	$ (13)

Derivatives (Net Derivatives as Reflected on the Balance Sheets) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Successor [Member]
Derivatives, Fair Value [Line Items]
Net derivatives as classified in the balance sheet	$ 4,807
Successor [Member] \| Other Current Assets [Member] \| Heating Oil [Member]
Derivatives, Fair Value [Line Items]
Net derivatives as classified in the balance sheet	4,646
Successor [Member] \| Coal Derivative Assets [Member] \| Coal [Member]
Derivatives, Fair Value [Line Items]
Net derivatives as classified in the balance sheet	262
Successor [Member] \| Coal Derivative Liabilities [Member] \| Coal [Member]
Derivatives, Fair Value [Line Items]
Net derivatives as classified in the balance sheet	$ (101)
Predecessor [Member]
Derivatives, Fair Value [Line Items]
Net derivatives as classified in the balance sheet		$ 9,052
Predecessor [Member] \| Other Current Assets [Member] \| Heating Oil [Member]
Derivatives, Fair Value [Line Items]
Net derivatives as classified in the balance sheet		1,017
Predecessor [Member] \| Coal Derivative Assets [Member] \| Coal [Member]
Derivatives, Fair Value [Line Items]
Net derivatives as classified in the balance sheet		8,035
Predecessor [Member] \| Coal Derivative Liabilities [Member] \| Coal [Member]
Derivatives, Fair Value [Line Items]
Net derivatives as classified in the balance sheet		$ 0

Derivatives (Effects of Derivatives on Measures of Financial Performance) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2016	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI (Effective Portion)	$ 0	$ (136)	$ 6,098	$ 5,745
Gains (Losses) Reclassified from Accumulated OCI into Income (Effective Portion)	0	397	9,575	2,643
Successor [Member] \| Coal [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives	(408)
Coal derivative settlements, non-hedging	116
Successor [Member] \| Heating Oil-Diesel Purchases [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized Gains (Losses)	827
Successor [Member] \| Heating Oil-Fuel Surchages [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized Gains (Losses)	0
Successor [Member] \| Natural Gas [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized Gains (Losses)	(91)
Successor [Member] \| Foreign Currency [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized Gains (Losses)	(9)
Predecessor [Member] \| Coal [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives		(1,662)	(3,883)	430
Coal derivative settlements, non-hedging		(476)	3,236	5,956
Predecessor [Member] \| Heating Oil-Diesel Purchases [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized Gains (Losses)		826	(8,294)	(7,848)
Predecessor [Member] \| Heating Oil-Fuel Surchages [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized Gains (Losses)		0		(405)
Predecessor [Member] \| Natural Gas [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized Gains (Losses)		(463)	878	0
Predecessor [Member] \| Foreign Currency [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized Gains (Losses)		(451)	(887)	0
Long [Member] \| Coal Contract [Member] \| Designated as Hedging Instrument [Member] \| Cost of Sales [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI (Effective Portion)	0	536	(6,718)	(5,097)
Gains (Losses) Reclassified from Accumulated OCI into Income (Effective Portion)	0	(1,237)	(9,060)	(2,693)
Short [Member] \| Coal Contract [Member] \| Designated as Hedging Instrument [Member] \| Sales Revenue, Net [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in OCI (Effective Portion)	0	(672)	12,816	10,842
Gains (Losses) Reclassified from Accumulated OCI into Income (Effective Portion)	$ 0	$ 1,634	$ 18,635	$ 5,336

Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Oct. 01, 2016	Dec. 31, 2015
Successor [Member]
Debt Instrument [Line Items]
Payroll and employee benefits	$ 58,468
Taxes other than income taxes	92,733
Interest	8,032
Sales contracts	5,114
Workers’ compensation	15,184
Asset retirement obligations	19,515
Other	6,194
Accrued Liabilities, Current	$ 205,240
Predecessor [Member]
Debt Instrument [Line Items]
Payroll and employee benefits			$ 58,423
Taxes other than income taxes			104,755
Interest			119,785
Sales contracts			3,852
Workers’ compensation			16,875
Asset retirement obligations		$ 17,290	13,795
Other			11,965
Accrued Liabilities, Current			$ 329,450

Debt and Financing Arrangements (Debt Outstanding) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Oct. 01, 2016	Jan. 11, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Debt issuance costs	$ (5,182)			$ (66,300)
Current maturities of debt				5,042,353
Term Loan Due 2021 [Member]
Debt Instrument [Line Items]
Term loan	$ 325,684
7.00% Senior Notes Due 2019 [Member]
Debt Instrument [Line Items]
Senior notes interest rate (percent)	7.00%		7.00%
8.00% Senior Secured Notes due 2019 [Member]
Debt Instrument [Line Items]
Senior notes interest rate (percent)	8.00%		8.00%
9.875% Senior Notes Due 2019 [Member]
Debt Instrument [Line Items]
Senior notes interest rate (percent)	9.875%		9.875%
7.25% Senior Notes Due 2020 [Member]
Debt Instrument [Line Items]
Senior notes interest rate (percent)	7.25%		7.25%
7.25% Senior Notes Due 2021 [Member]
Debt Instrument [Line Items]
Senior notes interest rate (percent)	7.25%		7.25%
Successor [Member]
Debt Instrument [Line Items]
Other	$ 37,195
Debt issuance costs	0
Total	362,879
Current maturities of debt	11,038
Long-term debt	351,841
Successor [Member] \| Term Loan Due 2021 [Member]
Debt Instrument [Line Items]
Term loan	325,684
Current maturities of debt		$ 3,300
Successor [Member] \| 7.00% Senior Notes Due 2019 [Member]
Debt Instrument [Line Items]
Senior notes	0
Successor [Member] \| 8.00% Senior Secured Notes due 2019 [Member]
Debt Instrument [Line Items]
Senior notes	0
Successor [Member] \| 9.875% Senior Notes Due 2019 [Member]
Debt Instrument [Line Items]
Senior notes	0
Successor [Member] \| 7.25% Senior Notes Due 2020 [Member]
Debt Instrument [Line Items]
Senior notes	0
Successor [Member] \| 7.25% Senior Notes Due 2021 [Member]
Debt Instrument [Line Items]
Senior notes	0
Predecessor [Member]
Debt Instrument [Line Items]
Other				47,134
Debt issuance costs				(64,857)
Total				5,073,306
Current maturities of debt				5,042,353
Long-term debt				30,953
Predecessor [Member] \| 7.00% Senior Notes Due 2019 [Member]
Debt Instrument [Line Items]
Senior notes interest rate (percent)		7.00%
Senior notes				1,000,000
Predecessor [Member] \| 8.00% Senior Secured Notes due 2019 [Member]
Debt Instrument [Line Items]
Senior notes interest rate (percent)		8.00%
Senior notes				350,000
Predecessor [Member] \| 9.875% Senior Notes Due 2019 [Member]
Debt Instrument [Line Items]
Senior notes interest rate (percent)		9.875%
Senior notes				365,600
Predecessor [Member] \| 7.25% Senior Notes Due 2020 [Member]
Debt Instrument [Line Items]
Senior notes interest rate (percent)		7.25%
Senior notes				500,000
Predecessor [Member] \| 7.25% Senior Notes Due 2021 [Member]
Debt Instrument [Line Items]
Senior notes interest rate (percent)		7.25%
Senior notes				1,000,000
Term Loan Due 2018 [Member] \| Loans Payable [Member]
Debt Instrument [Line Items]
Term loan	1,886,125			1,930,000
Term Loan Due 2018 [Member] \| Successor [Member] \| Loans Payable [Member]
Debt Instrument [Line Items]
Term loan	$ 0
Term Loan Due 2018 [Member] \| Predecessor [Member] \| Loans Payable [Member]
Debt Instrument [Line Items]
Term loan				$ 1,875,429

Debt and Financing Arrangements (Successor Company Debt) (Details) - USD ($)	Oct. 05, 2016	Dec. 31, 2016	Jan. 13, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Letters of credit outstanding				$ 21,300,000
Successor [Member]
Debt Instrument [Line Items]
Securitized accounts receivable			$ 200,000,000
Term of securitization agreement	3 years
Securitization agreement liquidity covenant amount	$ 175,000,000
Number of consecutive days under liquidity threshold	60 days
Successor [Member] \| Senior Notes [Member] \| New First Lien Debt Facility [Member]
Debt Instrument [Line Items]
Maximum amount of Debtors' liquidity	$ 300,000,000
Quarterly principal amortization payments	$ 816,250
Accrual of PIK interest (percent)	1.00%
Amount of voting equity interests of domestic subsidiaries guaranteed (percent)	100.00%
Amount of voting equity interests of foreign owned subsidiaries guaranteed (percent)	65.00%
Net cash proceeds of from debt issuances and other non-ordinary sales or dispositions (percent)	100.00%
Default to indebtedness	$ 35,000,000
Default to surety, reclamation or similar bond	50,000,000
Default to uninsured judgment	35,000,000
Uninsured losses or proceedings against	$ 35,000,000
Term of instrument	5 years
Successor [Member] \| Senior Notes [Member] \| New First Lien Debt Facility [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Basis spread on variable rate (percent)	9.00%
Successor [Member] \| Senior Notes [Member] \| New First Lien Debt Facility [Member] \| LIBOR [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Basis spread on variable rate (percent)	1.00%
Successor [Member] \| Senior Notes [Member] \| New First Lien Debt Facility [Member] \| Base Rate [Member]
Debt Instrument [Line Items]
Basis spread on variable rate (percent)	8.00%
Successor [Member] \| Line of Credit [Member] \| Extended Securitization Facility [Member]
Debt Instrument [Line Items]
Letters of credit outstanding		$ 154,000,000
Borrowing base		83,400,000
Cash collateral		71,000,000
Remaining availability		$ 0

Debt and Financing Arrangements (Predecessor Company Debt) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2016	Jan. 11, 2016
7.00% Senior Notes Due 2019 [Member]
Debt Instrument [Line Items]
Senior notes interest rate (percent)				7.00%	7.00%
7.25% Senior Notes Due 2020 [Member]
Debt Instrument [Line Items]
Senior notes interest rate (percent)				7.25%	7.25%
7.25% Senior Notes Due 2021 [Member]
Debt Instrument [Line Items]
Senior notes interest rate (percent)				7.25%	7.25%
9.875% Senior Notes Due 2019 [Member]
Debt Instrument [Line Items]
Senior notes interest rate (percent)				9.875%	9.875%
8.00% Senior Secured Notes due 2019 [Member]
Debt Instrument [Line Items]
Senior notes interest rate (percent)				8.00%	8.00%
Predecessor [Member]
Debt Instrument [Line Items]
2017				$ 11,038
2018				10,324
2019				11,479
2020				11,761
2021				317,987
Thereafter				290
Total				$ 362,879
Debt financing costs	$ 23,011	$ 0	$ 4,519
Professional fees	$ 2,200	24,200
Predecessor [Member] \| 7.00% Senior Notes Due 2019 [Member]
Debt Instrument [Line Items]
Senior notes interest rate (percent)	7.00%
Predecessor [Member] \| 7.25% Senior Notes Due 2020 [Member]
Debt Instrument [Line Items]
Senior notes interest rate (percent)	7.25%
Predecessor [Member] \| 7.25% Senior Notes Due 2021 [Member]
Debt Instrument [Line Items]
Senior notes interest rate (percent)	7.25%
Predecessor [Member] \| 9.875% Senior Notes Due 2019 [Member]
Debt Instrument [Line Items]
Senior notes interest rate (percent)	9.875%
Predecessor [Member] \| 8.00% Senior Secured Notes due 2019 [Member]
Debt Instrument [Line Items]
Senior notes interest rate (percent)	8.00%
Predecessor [Member] \| Line of Credit [Member]
Debt Instrument [Line Items]
Write off of deferred debt issuance cost		$ 3,700

Taxes (Narrative) (Details) - USD ($)	3 Months Ended	12 Months Ended
Taxes (Narrative) (Details) - USD ($)	Dec. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Oct. 02, 2016	Oct. 01, 2016
Operating Loss Carryforwards [Line Items]
Cancellation of debt income				$ 3,353,000,000
Decrease in operating loss carryforwards					$ 3,015,000,000
Decrease in tax basis of assets					3,200,000
Operating loss carryforwards	$ 931,100,000	$ 931,100,000
Annual limitation on operating loss use	29,800,000.0	29,800,000.0
Increase (decrease) in valuation allowance	(1,289,000,000)		$ 865,100,000
Additional valuation allowance	1,185,000,000	1,185,000,000
Net operating loss carryforwards	1,022,000,000	1,022,000,000	1,135,000,000
Interest and penalties accrued related to unrecognized tax benefits	$ 500,000	500,000	$ 1,700,000
Reductions as a result of lapses in the statute of limitations		$ 37,110,000
Alternative Minimum Tax Credits [Member]
Operating Loss Carryforwards [Line Items]
Decrease in tax credit carryforwards					92,000,000
Tax credit carryforwards				22,800,000
Capital Loss Carryforward [Member]
Operating Loss Carryforwards [Line Items]
Decrease in tax credit carryforwards					$ 59,200,000
Tax credit carryforwards				5,900,000
Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards				$ 931,100,000

Taxes (Schedule of Components of Income Tax) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2016	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
Predecessor [Member]
Current:
Federal		$ 0	$ 0	$ 0
State		7	3	25
Total current		7	3	25
Deferred:
Federal		(4,720)	(329,393)	18,535
State		87	(43,990)	7,074
Total deferred		(4,633)	(373,383)	25,609
Provision for (benefit from) income taxes		$ (4,626)	$ (373,380)	$ 25,634
Successor [Member]
Current:
Federal	$ 0
State	(252)
Total current	(252)
Deferred:
Federal	1,352
State	56
Total deferred	1,408
Provision for (benefit from) income taxes	$ 1,156

Taxes (Schedule of Effective Income Tax Rate Reconciliation) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2016	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
Predecessor [Member]
Income Tax Examination [Line Items]
Income tax provision (benefit) at statutory rate		$ 433,109	$ (1,150,283)	$ (186,452)
Percentage depletion allowance		(3,681)	(19,035)	(12,692)
State taxes, net of effect of federal taxes		(46,122)	(76,445)	(3,903)
Reversal of cancellation of indebtedness income		(1,493,162)	0	0
Worthless stock deduction		(80,077)	0	0
Change in valuation allowance		1,185,326	865,146	226,929
Other, net		(19)	7,237	1,752
Provision for (benefit from) income taxes		$ (4,626)	$ (373,380)	$ 25,634
Successor [Member]
Income Tax Examination [Line Items]
Income tax provision (benefit) at statutory rate	$ 12,112
Percentage depletion allowance	(4,292)
State taxes, net of effect of federal taxes	633
Reversal of cancellation of indebtedness income	0
Worthless stock deduction	0
Change in valuation allowance	(7,655)
Other, net	358
Provision for (benefit from) income taxes	$ 1,156

Taxes (Schedule of Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Income Tax Contingency [Line Items]
Net operating loss carryforwards	$ 1,022,000	$ 1,135,000
Predecessor [Member]
Income Tax Contingency [Line Items]
Net operating loss carryforwards		1,086,332
Alternative minimum tax credit carryforwards		120,994
Investment in tax partnerships & corporations		0
Reclamation and mine closure		121,276
Goodwill		38,671
Workers’ compensation		42,835
Share based compensation		22,612
Sales contracts		17,466
Retiree benefit plans		16,996
Advance royalties		18,751
Losses from disposed operations resulting from Patriot Coal bankruptcy		39,287
Other, primarily accrued liabilities		45,303
Gross deferred tax assets		1,570,523
Valuation allowance		(1,135,399)
Total deferred tax assets		435,124
Plant and equipment		389,169
Deferred development		41,047
Sales contracts		0
Other		4,706
Total deferred tax liabilities		434,922
Net deferred (asset) liability		$ (202)
Successor [Member]
Income Tax Contingency [Line Items]
Net operating loss carryforwards	376,293
Alternative minimum tax credit carryforwards	22,798
Investment in tax partnerships & corporations	604,914
Reclamation and mine closure	0
Goodwill	5,135
Workers’ compensation	0
Share based compensation	0
Sales contracts	0
Retiree benefit plans	4,013
Advance royalties	0
Losses from disposed operations resulting from Patriot Coal bankruptcy	0
Other, primarily accrued liabilities	30,103
Gross deferred tax assets	1,043,256
Valuation allowance	(1,021,553)
Total deferred tax assets	21,703
Plant and equipment	7,332
Deferred development	0
Sales contracts	12,658
Other	1,600
Total deferred tax liabilities	21,590
Net deferred (asset) liability	$ (113)

Taxes (Schedule of Gross Unrecognized Tax Benefits) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning Balance	$ 38,877	$ 34,709	$ 31,789
Additions based on tax positions related to the current year	2,709	4,168	2,920
Additions for tax positions of prior years	2,979
Reductions as a result of lapses in the statute of limitations	(37,110)
Ending Balance	$ 7,455	$ 38,877	$ 34,709

Asset Retirement Obligations (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
asset retirement obligations [Line Items]
Letters of credit outstanding		$ 21.3
Cash collateral for surety bond	$ 33.4
Asset retirement obligations [Member]
asset retirement obligations [Line Items]
Surety bonds outstanding		$ 528.3

Asset Retirement Obligations (Schedule of Asset Retirement Obligations) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2016	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
Successor [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	$ 354,326
Accretion expense	7,634
Obligations of divested operations	0
Adjustments to the liability from changes in estimates	0
Liabilities settled	(5,218)
Fresh start accounting adjustment	0
Ending Balance	356,742	$ 354,326
Current portion included in accrued expenses	(19,515)
Noncurrent liability	337,227
Predecessor [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	$ 354,326	410,454	$ 418,118
Accretion expense		24,321	33,680	$ 32,909
Obligations of divested operations		(14,702)	(334)
Adjustments to the liability from changes in estimates		3,003	(28,570)
Liabilities settled		(11,087)	(12,440)
Fresh start accounting adjustment		(57,663)	0
Ending Balance		354,326	410,454	$ 418,118
Current portion included in accrued expenses		(17,290)	(13,795)
Noncurrent liability		$ 337,036	$ 396,659

Fair Value Measurements (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of senior notes and other long-term debt, including amounts classified as current	$ 362.9	$ 937.1
Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Net unrealized gains related to level 3 financial instruments	$ 0.4

Fair Value Measurements (Summary of Financial Assets and Liabilities Accounted for at Fair Value) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Successor [Member]
Assets:
Investments in marketable securities	$ 90,209
Derivatives	4,908
Total assets	95,117
Liabilities:
Derivatives	101
Successor [Member] \| Level 1 [Member]
Assets:
Investments in marketable securities	2,137
Derivatives	262
Total assets	2,399
Liabilities:
Derivatives	(8)
Successor [Member] \| Level 2 [Member]
Assets:
Investments in marketable securities	88,072
Total assets	88,072
Liabilities:
Derivatives	0
Successor [Member] \| Level 3 [Member]
Assets:
Derivatives	4,646
Total assets	4,646
Liabilities:
Derivatives	$ 109
Predecessor [Member]
Assets:
Investments in marketable securities		$ 201,910
Derivatives		9,052
Total assets		210,962
Liabilities:
Derivatives		0
Predecessor [Member] \| Level 1 [Member]
Assets:
Investments in marketable securities		11,713
Derivatives		5,597
Total assets		17,310
Predecessor [Member] \| Level 2 [Member]
Assets:
Investments in marketable securities		190,197
Derivatives		1,023
Total assets		191,220
Liabilities:
Derivatives		0
Predecessor [Member] \| Level 3 [Member]
Assets:
Derivatives		2,432
Total assets		2,432
Liabilities:
Derivatives		$ 0

Fair Value Measurements (Summary of Change in the Fair Values of Financial Instruments Categorized as Level 3) (Details) - Level 3 [Member] - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2016	Oct. 01, 2016	Dec. 31, 2015
Successor [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	$ 3,842
Realized and unrealized losses recognized in earnings, net	926
Included in other comprehensive income	0
Purchases	1,225
Issuances	(34)
Settlements	(1,422)
Ending balance	4,537	$ 3,842
Predecessor [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	$ 3,842	2,432	$ 3,040
Realized and unrealized losses recognized in earnings, net		(1,686)	(8,602)
Included in other comprehensive income		0	(1,341)
Purchases		5,021	13,541
Issuances		(488)	(4,046)
Settlements		(1,437)	(160)
Ending balance		$ 3,842	$ 2,432

(Narrative) (Details)		3 Months Ended
(Narrative) (Details)	Aug. 04, 2015	Dec. 31, 2016 $ / shares shares	Oct. 05, 2016 $ / shares	Oct. 02, 2016 $ / shares shares	Dec. 31, 2015 $ / shares shares
Class of Stock [Line Items]
Warrants exercised		2,871
Successor [Member]
Class of Stock [Line Items]
Common stock, shares issued		25,002,000
Common stock, par value \| $ / shares		$ 0.01
Predecessor [Member]
Class of Stock [Line Items]
Common stock, shares issued					21,446,000
Common stock, par value \| $ / shares					$ 0.01
Reverse stock split conversion ratio	0.1
Class A Common Stock [Member]
Class of Stock [Line Items]
Common stock, shares issued				24,589,834
Common stock, par value \| $ / shares			$ 0.01
Class A Common Stock [Member] \| Successor [Member]
Class of Stock [Line Items]
Common stock, shares issued				24,589,834
Common stock, par value \| $ / shares				$ 0.01
Warrants issued				1,914,856
Class B Common Stock [Member]
Class of Stock [Line Items]
Common stock, shares issued				410,166
Common stock, par value \| $ / shares				$ 0.01
Class B Common Stock [Member] \| Successor [Member]
Class of Stock [Line Items]
Common stock, shares issued				410,166
Common stock, par value \| $ / shares				$ 0.01

Stock-Based Compensation and Other Incentive Plans (Narrative) (Details) shares in Millions, $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2016 USD ($) award shares	Oct. 01, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of award types granted in period \| award	3
Fresh-start accounting adjustment to incentive compensation	$ 3.7
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 1.0	$ 1.9	$ 5.9	$ 5.6
Time Based Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of award types granted in period \| award	2
Time Based Restricted Stock Units (RSUs) [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	1 year
Time Based Restricted Stock Units (RSUs) [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Performance Based Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of award types granted in period \| award	1
Vesting period	3 years
Volatility rate (percent)	58.00%
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense		0.2	$ 1.4	3.2
2016 Omnibus Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for incentive plan \| shares	3.0
Number of shares available for grant \| shares	2.6
Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Requisite service period			3 years
Compensation expense	$ 1.6	$ 7.2	$ 7.9	$ 10.1
Reduction in scheduled compensation payouts	6.0
Amounts unpaid under long term incentive plan	$ 13.9		$ 17.8

Stock-Based Compensation and Other Incentive Plans (Restricted Stock Unit Activity) (Details) - Restricted Stock Units (RSUs) [Member] shares in Thousands	3 Months Ended
	Dec. 31, 2016 $ / shares shares
Restricted Stock Common Shares
Outstanding at beginning of period (in shares) \| shares	0
Granted (in shares) \| shares	384
Forfeited (in shares) \| shares	0
Canceled (in shares) \| shares	0
Outstanding at end of period (in shares) \| shares	384
Weighted Average Grant Date Fair Value
Outstanding weighted average grant date fair value at beginning of period (in dollars per share) \| $ / shares	$ 0.00
Granted (in dollars per share) \| $ / shares	$ 72.00
Forfeited (in dollars per share) \| $ / shares	0.00
Canceled (in dollars per share) \| $ / shares	$ 0.00
Outstanding weighted average grant date fair value at end of period (in dollars per share) \| $ / shares	$ 72.00

Workers' Compensation Expense (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Reimbursable liabilities		$ 19.4
Insurance receivable, current		0.8
Insurance receivable, noncurrent		$ 18.6
Workers' Compensation [Member]
Defined Benefit Plan Disclosure [Line Items]
Surety bonds and letters of credit outstanding	$ 146.2

Workers' Compensation Expense (Worker's Compensation Expense) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2016	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
Successor [Member]
Accrued Workers' Compensation [Line Items]
Service cost	$ 1,583
Interest cost	1,126
Net amortization	0
Successor [Member] \| Workers' Compensation [Member]
Accrued Workers' Compensation [Line Items]
Total workers’ compensation expense	5,871
Successor [Member] \| Occupational Disease [Member]
Accrued Workers' Compensation [Line Items]
Service cost	1,583
Interest cost	1,126
Total occupational disease	2,709
Successor [Member] \| Traumatic Injury Claims and Assessments [Member]
Accrued Workers' Compensation [Line Items]
Traumatic injury claims and assessments	$ 3,162
Predecessor [Member]
Accrued Workers' Compensation [Line Items]
Service cost		$ 3,465	$ 4,282	$ 1,734
Interest cost		3,184	3,944	2,914
Net amortization		4,325	6,973	(216)
Predecessor [Member] \| Workers' Compensation [Member]
Accrued Workers' Compensation [Line Items]
Total workers’ compensation expense		17,602	31,980	24,356
Predecessor [Member] \| Occupational Disease [Member]
Accrued Workers' Compensation [Line Items]
Service cost		3,465	4,282
Interest cost		3,184	3,944
Total occupational disease		10,974	15,199	4,432
Predecessor [Member] \| Traumatic Injury Claims and Assessments [Member]
Accrued Workers' Compensation [Line Items]
Traumatic injury claims and assessments		$ 6,628	$ 16,781	$ 19,924

Workers' Compensation Expense (Schedule of Amounts Recognized in Balance Sheet) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Oct. 02, 2016	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
Accrued Workers' Compensation [Line Items]
Insurance receivable, current	$ 800
Successor [Member]
Accrued Workers' Compensation [Line Items]
Total obligations	199,752
Less amount included in accrued expenses	15,184
Noncurrent obligations	184,568
Predecessor [Member]
Accrued Workers' Compensation [Line Items]
Total obligations				$ 129,145
Less amount included in accrued expenses				16,875
Noncurrent obligations				112,270
Occupational Disease [Member] \| Successor [Member]
Accrued Workers' Compensation [Line Items]
Occupational disease costs	111,159	$ 119,710
Occupational Disease [Member] \| Predecessor [Member]
Accrued Workers' Compensation [Line Items]
Occupational disease costs			$ 119,710	90,836	$ 72,749
Workers' Compensation [Member] \| Successor [Member]
Accrued Workers' Compensation [Line Items]
Occupational disease costs	$ 88,593
Workers' Compensation [Member] \| Predecessor [Member]
Accrued Workers' Compensation [Line Items]
Occupational disease costs				$ 38,309

Workers' Compensation Expense (Occupational Disease Costs Activity and Assumptions) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2016	Jun. 30, 2016	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
Self Insurance Reserve [Roll Forward]
Curtailments		$ 3,600
Successor [Member]
Self Insurance Reserve [Roll Forward]
Service cost	$ 1,583
Interest cost	1,126
Predecessor [Member]
Self Insurance Reserve [Roll Forward]
Service cost			$ 3,465	$ 4,282	$ 1,734
Interest cost			3,184	3,944	2,914
Occupational Disease [Member] \| Successor [Member]
Self Insurance Reserve [Roll Forward]
Service cost	1,583
Interest cost	1,126
Curtailments	0
Actuarial (gain) loss	(9,675)
Benefit and administrative payments	(1,585)
Fresh start accounting adjustment	0
End of period	$ 111,159
Discount rate (percent)	4.31%
Occupational Disease [Member] \| Predecessor [Member]
Self Insurance Reserve [Roll Forward]
Beginning of period	$ 119,710	$ 90,836	90,836	72,749
Service cost			3,465	4,282
Interest cost			3,184	3,944
Curtailments			4,156
Actuarial (gain) loss			0	14,284
Benefit and administrative payments			(3,728)	(4,423)
Fresh start accounting adjustment			21,797	0
End of period			$ 119,710	$ 90,836	$ 72,749
Discount rate (percent)			3.80%	4.76%

Employee Benefit Plans (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2016	Oct. 01, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation of pension plans	$ 313.6		$ 313.6	$ 301.3
Health care cost trend rate assumed			6.70%
Ultimate trend rate			4.50%
Effect of one percentage point increase on postretirement benefit obligation			$ 11.1
Effect of one percentage point increase on postretirement benefit cost			$ 0.1
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations (percent)			55.00%
Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations (percent)			45.00%
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Contributions			$ 0.4
Other postretirement benefits payments	$ 3.5	$ 13.8		$ 20.5	$ 22.9

Employee Benefit Plans (Schedule of Defined Benefit Plans Disclosures) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2016	Jun. 30, 2016	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Curtailments		$ 3,600
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Value of Plan Assets at beginning of year		212,392	$ 212,392
Value of Plan Assets at end of year	$ 274,225			$ 212,392
Pension Benefits [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Value of Plan Assets at end of year	252,278
Predecessor [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Service cost			3,465	4,282	$ 1,734
Interest cost			3,184	3,944	2,914
Predecessor [Member] \| Pension Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligations at beginning of year	341,427	301,292	301,292	353,736
Service cost	0		0	9	21,478
Interest cost			9,338	14,604	17,070
Re-entry of former Magnum employees			0	0
Settlements			0	0
Curtailments			454
Benefits paid			(8,699)	(61,955)
Other-primarily actuarial gain			0	(5,102)
Benefit Obligations at end of year			341,427	301,292	353,736
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Value of Plan Assets at beginning of year	292,726	273,499	273,499	336,709
Actual return on plan assets			27,811	(1,679)
Employer contributions			115	424
Benefits paid			(8,699)	(61,955)
Value of Plan Assets at end of year			292,726	273,499	336,709
Accrued benefit cost			(48,701)	(27,793)
Prior service credit (cost)			0	0
Accumulated gain (loss)			0	(16,769)
Total not yet recognized as a component of net periodic benefit cost			0	(16,769)
Current liability			(420)	(420)
Noncurrent liability			(48,281)	(27,373)
Pension and Other Postretirement Defined Benefit Plans, Liabilities			(48,701)	(27,793)
Fresh start accounting adjustment			39,042	0
Predecessor [Member] \| Other Postretirement Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligations at beginning of year	120,311	103,460	103,460	36,098
Service cost			393	866	1,649
Interest cost			3,223	1,904	1,841
Re-entry of former Magnum employees			0	85,843
Settlements			0	0
Curtailments			714	0
Benefits paid			(8,273)	(3,646)
Other-primarily actuarial gain			0	(17,605)
Benefit Obligations at end of year			120,311	103,460	36,098
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Value of Plan Assets at beginning of year	0	$ 0	0	0
Actual return on plan assets			0	0
Employer contributions			8,273	3,646
Benefits paid			(8,273)	(3,646)
Value of Plan Assets at end of year			0	0	$ 0
Accrued benefit cost			(120,311)	(103,460)
Prior service credit (cost)			0	26,944
Accumulated gain (loss)			0	11,313
Total not yet recognized as a component of net periodic benefit cost			0	38,257
Current liability			(8,352)	(3,650)
Noncurrent liability			(111,959)	(99,810)
Pension and Other Postretirement Defined Benefit Plans, Liabilities			(120,311)	$ (103,460)
Fresh start accounting adjustment			20,794
Successor [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Service cost	1,583
Interest cost	1,126
Successor [Member] \| Pension Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligations at beginning of year	341,427
Service cost	0
Interest cost	2,768
Re-entry of former Magnum employees	0
Settlements	(135)
Curtailments	0
Benefits paid	(11,009)
Other-primarily actuarial gain	(19,422)
Benefit Obligations at end of year	313,629		341,427
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Value of Plan Assets at beginning of year	292,726
Actual return on plan assets	(7,899)
Employer contributions	407
Benefits paid	(11,009)
Value of Plan Assets at end of year	274,225		292,726
Accrued benefit cost	(39,404)
Prior service credit (cost)	0
Accumulated gain (loss)	6,751
Total not yet recognized as a component of net periodic benefit cost	6,751
Current liability	(520)
Noncurrent liability	(38,884)
Pension and Other Postretirement Defined Benefit Plans, Liabilities	(39,404)
Fresh start accounting adjustment	0
Successor [Member] \| Other Postretirement Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligations at beginning of year	120,311
Service cost	180
Interest cost	978
Re-entry of former Magnum employees	0
Settlements	0
Curtailments	0
Benefits paid	(1,962)
Other-primarily actuarial gain	(7,640)
Benefit Obligations at end of year	111,867		120,311
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Value of Plan Assets at beginning of year	0
Employer contributions	1,962
Benefits paid	(1,962)
Value of Plan Assets at end of year	0		$ 0
Accrued benefit cost	(111,867)
Prior service credit (cost)	0
Accumulated gain (loss)	7,640
Total not yet recognized as a component of net periodic benefit cost	7,640
Current liability	(10,422)
Noncurrent liability	(101,445)
Pension and Other Postretirement Defined Benefit Plans, Liabilities	(111,867)
Fresh start accounting adjustment	$ 0

Employee Benefit Plans (Schedule of Net Benefit Costs) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2016	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
Predecessor [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		$ 3,465	$ 4,282	$ 1,734
Interest cost		3,184	3,944	2,914
Predecessor [Member] \| Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0	0	9	21,478
Interest cost		9,338	14,604	17,070
Curtailments		454	0	(25,368)
Settlements		0	2,656	646
Expected return on plan assets		(13,623)	(20,367)	(23,756)
Amortization of prior service credits		0	0	(257)
Amortization of other actuarial losses (gains)		3,973	8,850	3,128
Total net benefit		142	5,752	(7,059)
Predecessor [Member] \| Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		393	866	1,649
Interest cost		3,223	1,904	1,841
Curtailments		(970)	0	0
Settlements		0	0	0
Expected return on plan assets		0	0	0
Amortization of prior service credits		(7,854)	(8,335)	(10,003)
Amortization of other actuarial losses (gains)		(849)	(2,109)	(761)
Total net benefit		$ (6,057)	$ (7,674)	$ (7,274)
Successor [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1,583
Interest cost	1,126
Successor [Member] \| Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0
Interest cost	2,768
Curtailments	0
Settlements	(135)
Expected return on plan assets	(4,770)
Amortization of prior service credits	0
Amortization of other actuarial losses (gains)	0
Total net benefit	(2,137)
Successor [Member] \| Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	180
Interest cost	978
Curtailments	0
Settlements	0
Expected return on plan assets	0
Amortization of prior service credits	0
Amortization of other actuarial losses (gains)	0
Total net benefit	$ 1,158

Employee Benefit Plans (Schedule of Assumptions Used to Calculate Benefit Obligations) (Details)	Dec. 31, 2016	Oct. 01, 2016	Dec. 31, 2015
Predecessor [Member] \| Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate		339.00%	459.00%
Predecessor [Member] \| Other Postretirement Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate		337.00%	457.00%
Successor [Member] \| Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate			395.00%
Successor [Member] \| Other Postretirement Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	393.00%

Employee Benefit Plans (Schedule of Assumptions Used) (Details)			3 Months Ended						6 Months Ended			9 Months Ended	12 Months Ended
	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2016	Oct. 01, 2016	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2014	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
Successor [Member] \| Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	3.95%		3.39%
Expected return on plan assets			685.00%
Successor [Member] \| Other Postretirement Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate			337.00%
Predecessor [Member] \| Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate		4.60%		3.80%	4.41%	4.61%	4.14%	4.23%	4.59%	4.15%	5.08%
Expected return on plan assets												685.00%	700.00%	775.00%
Predecessor [Member] \| Other Postretirement Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate				5.70%					3.80%				391.00%	458.00%

Employee Benefit Plans (Schedule of Allocation of Plan Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Other liabilities	$ (22,170)
Total fair value of plan assets	274,225	$ 212,392
Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	77,022	74,051
Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	156,015	119,706
Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	19,241	18,635
U.S. Small-Cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	13,520	11,640
U.S. Small-Cap [Member] \| Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	13,520	11,640
U.S. Mid-Cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	29,687	28,524
U.S. Mid-Cap [Member] \| Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	9,422	10,979
U.S. Mid-Cap [Member] \| Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	20,265	17,545
U.S. Large-Cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	70,226	67,244
U.S. Large-Cap [Member] \| Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	34,107	33,249
U.S. Large-Cap [Member] \| Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	36,119	33,995
Non-U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	18,937	18,785
Non-U.S. [Member] \| Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	18,937	18,785
U.S. Government Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	26,519	18,844
U.S. Government Securities [Member] \| Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	19,973	18,183
U.S. Government Securities [Member] \| Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	6,546	661
Non-U.S. Government Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	1,567	766
Non-U.S. Government Securities [Member] \| Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	1,567	766
U.S. governement asset and mortgage backed securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	1,074	1,056
U.S. governement asset and mortgage backed securities [Member] \| Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	1,074	1,056
Corporate fixed income [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	58,191	39,939
Corporate fixed income [Member] \| Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	58,191	39,939
State and Local Government Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	6,406	5,725
State and Local Government Securities [Member] \| Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	6,406	5,725
Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	26,151	19,869
Other Investments [Member] \| Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	6,910	1,234
Other Investments [Member] \| Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	19,241	$ 18,635
Other fixed income [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	35,519
Short-term Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan assets	$ 8,598

Employee Benefit Plans (Summary of Estimated Future Benefit Payments) (Details) $ in Thousands	Dec. 31, 2015 USD ($)
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
2017	$ 19,403
2018	21,117
2019	20,763
2020	21,209
2021	21,917
Thereafter	102,619
Total	207,028
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
2017	12,300
2018	12,716
2019	13,033
2020	13,408
2021	13,763
Thereafter	64,920
Total	$ 130,140

Earnings (Loss) Per Common Share (Weighted Average Number of Shares) (Details) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended								9 Months Ended	12 Months Ended
	Oct. 01, 2016	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
Predecessor [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net income (loss)	$ 1,676,091		$ (51,421)	$ (175,887)	$ (206,702)	$ (632,368)	$ (1,999,476)	$ (168,103)	$ (113,195)	$ 1,242,081	$ (2,913,142)	$ (558,353)
Less: earnings allocated to participating securities										0	0	0
Net income (loss) attributable to common shareholders, after earnings allocated to participating securities										$ 1,242,081	$ (2,913,142)	$ (558,353)
Basic weighted average shares outstanding										21,293	21,285	21,222
Effect of dilutive securities										20	0	0
Diluted weighted average shares outstanding										21,313	21,285	21,222
Successor [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net income (loss)		$ 33,449
Less: earnings allocated to participating securities		(217)
Net income (loss) attributable to common shareholders, after earnings allocated to participating securities		$ 33,232
Basic weighted average shares outstanding		25,002
Effect of dilutive securities		467
Diluted weighted average shares outstanding		25,469

Leases (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
Leases (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
lease payments [Line Items]
Capital Lease Obligations	$ 0.0		$ 40.0
Rental expense	5.0	$ 19.4	28.4	$ 42.1
Royalty expense	45.3	$ 116.4	$ 227.7	$ 242.5
lease [Member]
lease payments [Line Items]
Surety bonds outstanding	$ 32.6

Leases (Schedule of Lease Minimum Payments) (Details) $ in Thousands	Dec. 31, 2016 USD ($)
Property Subject to Operating Lease [Member]
lease payments [Line Items]
2017	$ 14,653
2018	14,485
2019	5,321
2020	2,260
2021	1,985
Thereafter	10,317
Total	49,021
Royalty [Member]
lease payments [Line Items]
2017	3,994
2018	6,021
2019	6,105
2020	7,147
2021	7,809
Thereafter	46,499
Total	$ 77,575

Risk Concentrations (Narrative) (Details) T in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) T	Dec. 31, 2015 USD ($)
Concentration Risk [Line Items]
Tons of coal sold \| T	93.9
Percentage of tons sold under long term contract	76.00%
Long term contracts percentage of company revenue	62.00%
Long-term contracts, life term, minimum	1 year
Long-term contracts, life term, maximum	5 years
Electric Utilities [Member]
Concentration Risk [Line Items]
Receivables	$ 96.0	$ 83.8
Percentage of total trade accounts receivable	52.00%	72.00%
Domestic And Foreign Steel Producers [Member]
Concentration Risk [Line Items]
Trade accounts receivable (net of allowance for doubtful accounts of $0.0 million and $7.8 million, respectively)	$ 88.0	$ 32.8
Trade receivables, percentage	48.00%	28.00%

Risk Concentrations (Schedule of Foreign Revenues) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2016	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
Successor [Member]
foreign revenue [Line Items]
Sales to customers in foreign countries	$ 174,097
Successor [Member] \| Europe [Member]
foreign revenue [Line Items]
Sales to customers in foreign countries	61,408
Successor [Member] \| Asia [Member]
foreign revenue [Line Items]
Sales to customers in foreign countries	55,634
Successor [Member] \| North America [Member]
foreign revenue [Line Items]
Sales to customers in foreign countries	43,831
Successor [Member] \| Central and South America [Member]
foreign revenue [Line Items]
Sales to customers in foreign countries	13,224
Successor [Member] \| Brokered Sales [Member]
foreign revenue [Line Items]
Sales to customers in foreign countries	$ 0
Predecessor [Member]
foreign revenue [Line Items]
Sales to customers in foreign countries		$ 280,879	$ 395,323	$ 611,917
Predecessor [Member] \| Europe [Member]
foreign revenue [Line Items]
Sales to customers in foreign countries		113,888	170,314	277,565
Predecessor [Member] \| Asia [Member]
foreign revenue [Line Items]
Sales to customers in foreign countries		68,536	96,523	156,057
Predecessor [Member] \| North America [Member]
foreign revenue [Line Items]
Sales to customers in foreign countries		56,594	40,315	78,445
Predecessor [Member] \| Central and South America [Member]
foreign revenue [Line Items]
Sales to customers in foreign countries		41,861	55,323	20,496
Predecessor [Member] \| Brokered Sales [Member]
foreign revenue [Line Items]
Sales to customers in foreign countries		$ 0	$ 32,848	$ 79,354

Commitments and Contingencies (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2016
Loss Contingencies [Line Items]
Amount accrued		$ 2.8		$ 2.2
Amount accrued current portion		2.8		2.2
2017				$ 48.0
Transportation capacity agreements	$ 1.6	$ 52.9	$ 36.5

Segment Information (Schedule of Operating Segment Results) (Details) - USD ($) $ in Thousands	3 Months Ended								9 Months Ended	12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
Successor [Member]
Segment Reporting Information [Line Items]
Revenues	$ 575,688
Adjusted EBITDAR	94,497
Depreciation, depletion and amortization	32,604
Accretion on asset retirement obligations	7,634
Total assets	2,136,597
Capital expenditures	15,214
Successor [Member] \| Operating Segments [Member] \| PRB [Member]
Segment Reporting Information [Line Items]
Revenues	275,703
Adjusted EBITDAR	55,765
Depreciation, depletion and amortization	9,949
Accretion on asset retirement obligations	5,049
Total assets	446,775
Capital expenditures	934
Successor [Member] \| Operating Segments [Member] \| APP [Member]
Segment Reporting Information [Line Items]
Revenues	200,377
Adjusted EBITDAR	30,819
Depreciation, depletion and amortization	18,287
Accretion on asset retirement obligations	528
Total assets	576,793
Capital expenditures	13,329
Successor [Member] \| Operating Segments [Member] \| Other Thermal [Member]
Segment Reporting Information [Line Items]
Revenues	97,382
Adjusted EBITDAR	31,159
Depreciation, depletion and amortization	3,911
Accretion on asset retirement obligations	540
Total assets	129,602
Capital expenditures	684
Successor [Member] \| Corporate, Other and Elimination
Segment Reporting Information [Line Items]
Revenues	2,226
Adjusted EBITDAR	(23,246)
Depreciation, depletion and amortization	457
Accretion on asset retirement obligations	1,517
Total assets	983,427
Capital expenditures	$ 267
Predecessor [Member]
Segment Reporting Information [Line Items]
Revenues		$ 550,305	$ 420,298	$ 428,106	$ 563,249	$ 688,544	$ 644,462	$ 677,005	$ 1,398,709	$ 2,573,260	$ 2,937,119
Adjusted EBITDAR									87,303	283,797	313,052
Depreciation, depletion and amortization									191,581	379,345	418,748
Accretion on asset retirement obligations									24,321	33,680	32,909
Total assets					5,041,881				2,123,829	5,041,881	8,346,362
Capital expenditures									82,434	119,024	147,286
Predecessor [Member] \| Operating Segments [Member] \| PRB [Member]
Segment Reporting Information [Line Items]
Revenues									726,747	1,448,440	1,490,377
Adjusted EBITDAR									113,185	281,039	218,731
Depreciation, depletion and amortization									100,151	176,257	168,522
Accretion on asset retirement obligations									16,940	22,156	20,748
Total assets					1,648,916				456,711	1,648,916	1,762,326
Capital expenditures									612	21,228	21,399
Predecessor [Member] \| Operating Segments [Member] \| APP [Member]
Segment Reporting Information [Line Items]
Revenues									437,069	637,941	743,973
Adjusted EBITDAR									11,851	70,450	112,719
Depreciation, depletion and amortization									55,311	133,463	163,644
Accretion on asset retirement obligations									1,765	2,267	2,089
Total assets					772,439				619,154	772,439	2,339,739
Capital expenditures									17,296	24,787	46,771
Predecessor [Member] \| Operating Segments [Member] \| Other Thermal [Member]
Segment Reporting Information [Line Items]
Revenues									213,052	428,809	535,783
Adjusted EBITDAR									31,448	42,734	78,238
Depreciation, depletion and amortization									32,310	47,786	52,991
Accretion on asset retirement obligations									1,988	2,658	2,412
Total assets					366,610				131,173	366,610	406,296
Capital expenditures									3,895	11,277	14,843
Predecessor [Member] \| Corporate, Other and Elimination
Segment Reporting Information [Line Items]
Revenues									21,841	58,070	166,986
Adjusted EBITDAR									(69,181)	(110,426)	(96,636)
Depreciation, depletion and amortization									3,809	21,839	33,591
Accretion on asset retirement obligations									3,628	6,599	7,660
Total assets					$ 2,253,916				916,791	2,253,916	3,838,001
Capital expenditures									$ 60,631	$ 61,732	$ 64,273

Segment Information (Reconciliation of Segment Income from Operations to Consolidated Income Before Income Taxes) (Details) - USD ($) $ in Thousands		3 Months Ended								6 Months Ended	9 Months Ended	12 Months Ended
	Oct. 01, 2016	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2015	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Asset impairment and mine closure costs						$ (488,900)	$ (2,100,000)	$ (19,100)		$ (2,600,000)
Predecessor [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDAR											$ 87,303	$ 283,797	$ 313,052
Depreciation, depletion and amortization											(191,581)	(379,345)	(418,748)
Accretion on asset retirement obligations											(24,321)	(33,680)	(32,909)
Amortization of sales contracts, net											728	8,811	13,187
Asset impairment and mine closure costs			$ (46)	$ (43,701)	$ (85,520)	$ (488,865)	$ (2,120,292)	$ (19,146)	$ 0		(129,267)	(2,628,303)	(24,113)
Losses from disposed operations resulting from Patriot Coal bankruptcy											0	(116,343)	0
Interest expense, net											(133,235)	(393,549)	(383,188)
Net loss resulting from early retirement of debt and debt restructuring											(2,213)	(27,910)	0
Reorganization items, net	$ 1,676,091		$ (20,904)	$ (21,271)	$ (3,875)						1,630,041	0	0
Fresh start coal inventory fair value adjustment											0	0	0
Income (loss) before income taxes											$ 1,237,455	$ (3,286,522)	$ (532,719)
Successor [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDAR		$ 94,497
Depreciation, depletion and amortization		(32,604)
Accretion on asset retirement obligations		(7,634)
Amortization of sales contracts, net		(796)
Asset impairment and mine closure costs		0
Losses from disposed operations resulting from Patriot Coal bankruptcy		0
Interest expense, net		(10,754)
Net loss resulting from early retirement of debt and debt restructuring		0
Reorganization items, net		(759)
Fresh start coal inventory fair value adjustment		(7,345)
Income (loss) before income taxes		$ 34,605

Quarterly Selected Financial Data (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended								6 Months Ended	9 Months Ended	12 Months Ended
	Oct. 01, 2016	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2015	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Asset impairment and mine closure costs						$ 488,900	$ 2,100,000	$ 19,100		$ 2,600,000
Predecessor [Member]
Class of Stock [Line Items]
Revenues			$ 550,305	$ 420,298	$ 428,106	563,249	688,544	644,462	$ 677,005		$ 1,398,709	$ 2,573,260	$ 2,937,119
Gross profit (loss)			31,042	(56,469)	(53,325)	(44,964)	47,275	(16,507)	14,256
Asset impairment and mine closure costs			46	43,701	85,520	488,865	2,120,292	19,146	0		129,267	2,628,303	24,113
Income (loss) from operations			11,795	(110,521)	(158,412)	(539,033)	(2,236,772)	(69,546)	(19,712)		(257,138)	(2,865,063)	(149,531)
Reorganization items, net	$ 1,676,091		(20,904)	(21,271)	(3,875)						1,630,041	0	0
Net income (loss)	$ 1,676,091		$ (51,421)	$ (175,887)	$ (206,702)	$ (632,368)	$ (1,999,476)	$ (168,103)	$ (113,195)		$ 1,242,081	$ (2,913,142)	$ (558,353)
Diluted earnings per common share (in dollars per share)	$ 78.66		$ (2.41)	$ (8.26)	$ (9.71)	$ (29.70)	$ (93.91)	$ (7.93)	$ (5.32)		$ 58.28	$ (136.86)	$ (26.31)
Successor [Member]
Class of Stock [Line Items]
Revenues		$ 575,688
Gross profit (loss)		64,458
Asset impairment and mine closure costs		0
Income (loss) from operations		46,118
Reorganization items, net		(759)
Net income (loss)		$ 33,449
Diluted earnings per common share (in dollars per share)		$ 1.31

Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2016	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
Successor [Member] \| Other assets — other notes and accounts receivable
Reserves deducted from asset accounts:
Balance at Beginning of Year	$ 0
Additions (Reductions) Charged to Costs and Expenses	0
Charged to Other Accounts	0
Deductions	0
Balance at End of Year	0	$ 0
Successor [Member] \| Current assets — supplies and inventory
Reserves deducted from asset accounts:
Balance at Beginning of Year	0
Additions (Reductions) Charged to Costs and Expenses	0
Charged to Other Accounts	0
Deductions	0
Balance at End of Year	0	0
Successor [Member] \| Deferred income taxes
Reserves deducted from asset accounts:
Balance at Beginning of Year	1,033,982
Additions (Reductions) Charged to Costs and Expenses	(7,655)
Charged to Other Accounts	0
Deductions	0
Balance at End of Year	1,026,327	1,033,982
Predecessor [Member] \| Other assets — other notes and accounts receivable
Reserves deducted from asset accounts:
Balance at Beginning of Year	0	7,842	$ 159	$ 775
Additions (Reductions) Charged to Costs and Expenses		0	7,683	0
Charged to Other Accounts		0	0	0
Deductions		7,842	0	616
Balance at End of Year		0	7,842	159
Predecessor [Member] \| Current assets — supplies and inventory
Reserves deducted from asset accounts:
Balance at Beginning of Year	0	5,991	6,625	8,446
Additions (Reductions) Charged to Costs and Expenses		844	431	580
Charged to Other Accounts		(5,060)	0	(76)
Deductions		1,775	1,065	2,325
Balance at End of Year		0	5,991	6,625
Predecessor [Member] \| Deferred income taxes
Reserves deducted from asset accounts:
Balance at Beginning of Year	$ 1,033,982	1,135,399	270,251	43,322
Additions (Reductions) Charged to Costs and Expenses		(101,417)	865,148	226,929
Charged to Other Accounts			0	0
Deductions		0	0	0
Balance at End of Year		$ 1,033,982	$ 1,135,399	$ 270,251

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies The Company accrues for cost related to contingencies when a loss is probable and the amount is reasonably determinable. Disclosure of contingencies is included in the financial statements when it is at least reasonably possible that a material loss or an additional material loss in excess of amounts already accrued may be incurred. The Company is a party to numerous claims and lawsuits with respect to various matters. As of December 31, 2016 and 2015, the Company had accrued $2.2 million and $2.8 million, respectively, for all legal matters, including $2.2 million and $2.8 million, respectively, classified as current. The ultimate resolution of any such legal matter could result in outcomes which may be materially different from amounts the Company has accrued for such matters. 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 $48.0 million in 2017, and is immaterial thereafter. The Company recognized expense relating to transportation capacity agreements of $1.6 million during the period January 1 through October 1, 2016; and $52.9 million and $36.5 million during the years ended December 31, 2015 and 2014, respectively.