Supplemental Consolidating Financial Information (Schedule of Consolidating Statements of Operations) (Details) - USD ($) $ in Thousands		3 Months Ended								6 Months Ended	12 Months Ended
	Dec. 17, 2013	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Income Statements, Captions [Line Items]
Revenues		$ 563,249	$ 688,544	$ 644,462	$ 677,005	$ 745,192	$ 742,180	$ 713,776	$ 735,971		$ 2,573,260	$ 2,937,119	$ 3,014,357
Costs, expenses and other
Cost of sales (exclusive of items shown separately below)											2,206,433	2,566,193	2,663,136
Depreciation, depletion and amortization											379,345	418,748	426,442
Amortization of acquired sales contracts, net											(8,811)	(13,187)	(9,457)
Change in fair value of coal derivatives and coal trading activities, net											(1,583)	(3,686)	7,845
Asset impairment and mine closure costs		488,865	2,120,292	19,146	0	17,541	5,060	1,512	0	$ 2,600,000	2,628,303	24,113	220,879
Losses from disposed operations resulting from Patriot Coal bankruptcy											116,343	0	0
Goodwill impairment											0	0	265,423
Selling, general and administrative expenses											98,783	114,223	133,448
Other operating expense (income), net											19,510	(19,754)	(30,218)
Total operating expenses											5,438,323	3,086,650	3,677,498
Loss from investment in subsidiaries											0	0	0
Loss from operations		(539,033)	(2,236,772)	(69,546)	(19,712)	(5,303)	(35,300)	(35,805)	(73,123)		(2,865,063)	(149,531)	(663,141)
Interest expense, net
Interest expense											(397,979)	(390,946)	(381,267)
Interest and investment income											4,430	7,758	6,603
Interest expense, net											(393,549)	(383,188)	(374,664)
Other Nonoperating Income (Expense) [Abstract]
Net loss resulting from early retirement of debt and debt restructuring	$ 41,000										27,910	0	42,921
Loss from continuing operations before income taxes											(3,286,522)	(532,719)	(1,080,726)
Provision for (benefit from) income taxes											373,380	(25,634)	335,498
Loss from continuing operations											(2,913,142)	(558,353)	(745,228)
Income from discontinued operations, including gain on sale - net of tax											0	0	(103,396)
Net loss		$ (632,368)	$ (1,999,476)	$ (168,103)	$ (113,195)	$ (240,135)	$ (97,218)	$ (96,860)	$ (124,140)		(2,913,142)	(558,353)	(641,832)
Total comprehensive income (loss)											(2,918,198)	(592,804)	(587,633)
Parent/Issuer [Member]
Condensed Income Statements, Captions [Line Items]
Revenues											0	0	0
Costs, expenses and other
Cost of sales (exclusive of items shown separately below)											22,378	3,016	9,117
Depreciation, depletion and amortization											3,775	5,154	5,949
Amortization of acquired sales contracts, net											0	0	0
Change in fair value of coal derivatives and coal trading activities, net											0	0	0
Asset impairment and mine closure costs											15,437	3,642	78,150
Losses from disposed operations resulting from Patriot Coal bankruptcy											116,343
Goodwill impairment													0
Selling, general and administrative expenses											69,384	79,902	88,820
Other operating expense (income), net											5,869	(4,480)	4,209
Total operating expenses											233,186	87,234	186,245
Loss from investment in subsidiaries											(2,574,565)	(13,085)	(328,889)
Loss from operations											(2,807,751)	(100,319)	(515,134)
Interest expense, net
Interest expense											(478,432)	(463,823)	(449,614)
Interest and investment income											27,510	31,389	30,285
Interest expense, net											(450,922)	(432,434)	(419,329)
Other Nonoperating Income (Expense) [Abstract]
Net loss resulting from early retirement of debt and debt restructuring											27,910		42,921
Loss from continuing operations before income taxes											(3,286,583)	(532,753)	(977,384)
Provision for (benefit from) income taxes											373,441	(25,600)	335,552
Loss from continuing operations													(641,832)
Income from discontinued operations, including gain on sale - net of tax													0
Net loss											(2,913,142)	(558,353)	(641,832)
Total comprehensive income (loss)											(2,918,198)	(592,804)	(587,633)
Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Revenues											2,573,260	2,937,119	3,014,357
Costs, expenses and other
Cost of sales (exclusive of items shown separately below)											2,186,804	2,566,572	2,657,583
Depreciation, depletion and amortization											375,568	413,559	420,458
Amortization of acquired sales contracts, net											(8,811)	(13,187)	(9,457)
Change in fair value of coal derivatives and coal trading activities, net											(1,583)	(3,686)	7,845
Asset impairment and mine closure costs											2,612,866	20,471	142,729
Losses from disposed operations resulting from Patriot Coal bankruptcy											0
Goodwill impairment													265,423
Selling, general and administrative expenses											25,737	29,739	39,825
Other operating expense (income), net											13,021	(15,726)	(34,856)
Total operating expenses											5,203,602	2,997,742	3,489,550
Loss from investment in subsidiaries											0	0	0
Loss from operations											(2,630,342)	(60,623)	(475,193)
Interest expense, net
Interest expense											(26,284)	(26,137)	(24,747)
Interest and investment income											82,881	74,511	68,248
Interest expense, net											56,597	48,374	43,501
Other Nonoperating Income (Expense) [Abstract]
Net loss resulting from early retirement of debt and debt restructuring											0		0
Loss from continuing operations before income taxes											(2,573,745)	(12,249)	(431,692)
Provision for (benefit from) income taxes											0	0	0
Loss from continuing operations													(431,692)
Income from discontinued operations, including gain on sale - net of tax													(103,396)
Net loss											(2,573,745)	(12,249)	(328,296)
Total comprehensive income (loss)											(2,579,601)	(34,439)	(304,278)
Non-Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Revenues											0	0	0
Costs, expenses and other
Cost of sales (exclusive of items shown separately below)											0	0	0
Depreciation, depletion and amortization											2	35	35
Amortization of acquired sales contracts, net											0	0	0
Change in fair value of coal derivatives and coal trading activities, net											0	0	0
Asset impairment and mine closure costs											0	0	0
Losses from disposed operations resulting from Patriot Coal bankruptcy											0
Goodwill impairment													0
Selling, general and administrative expenses											5,725	6,626	7,038
Other operating expense (income), net											(4,192)	(4,987)	(5,370)
Total operating expenses											1,535	1,674	1,703
Loss from investment in subsidiaries											0	0	0
Loss from operations											(1,535)	(1,674)	(1,703)
Interest expense, net
Interest expense											(4,916)	(4,259)	(4,214)
Interest and investment income											5,692	5,131	5,378
Interest expense, net											776	872	1,164
Other Nonoperating Income (Expense) [Abstract]
Net loss resulting from early retirement of debt and debt restructuring											0		0
Loss from continuing operations before income taxes											(759)	(802)	(539)
Provision for (benefit from) income taxes											(61)	(34)	(54)
Loss from continuing operations													(593)
Income from discontinued operations, including gain on sale - net of tax													0
Net loss											(820)	(836)	(593)
Total comprehensive income (loss)											(820)	(836)	(593)
Eliminations [Member]
Condensed Income Statements, Captions [Line Items]
Revenues											0	0	0
Costs, expenses and other
Cost of sales (exclusive of items shown separately below)											(2,749)	(3,395)	(3,564)
Depreciation, depletion and amortization											0	0	0
Amortization of acquired sales contracts, net											0	0	0
Change in fair value of coal derivatives and coal trading activities, net											0	0	0
Asset impairment and mine closure costs											0	0	0
Losses from disposed operations resulting from Patriot Coal bankruptcy											0
Goodwill impairment													0
Selling, general and administrative expenses											(2,063)	(2,044)	(2,235)
Other operating expense (income), net											4,812	5,439	5,799
Total operating expenses											0	0	0
Loss from investment in subsidiaries											2,574,565	13,085	328,889
Loss from operations											2,574,565	13,085	328,889
Interest expense, net
Interest expense											111,653	103,273	97,308
Interest and investment income											(111,653)	(103,273)	(97,308)
Interest expense, net											0	0	0
Other Nonoperating Income (Expense) [Abstract]
Net loss resulting from early retirement of debt and debt restructuring											0		0
Loss from continuing operations before income taxes											2,574,565	13,085	328,889
Provision for (benefit from) income taxes											0	0	0
Loss from continuing operations													328,889
Income from discontinued operations, including gain on sale - net of tax													0
Net loss											2,574,565	13,085	328,889
Total comprehensive income (loss)											$ 2,580,421	$ 35,275	$ 304,871