Supplemental Consolidating Financial Information (Schedule Of Condensed Consolidating Statements Of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Revenues	$ 428,106	$ 677,005
Costs, expenses and other
Cost of sales (exclusive of items shown separately below)	419,316	562,322
Depreciation, depletion and amortization	63,699	104,874
Amortization of acquired sales contracts, net	(833)	(3,390)
Change in fair value of coal derivatives and coal trading activities, net	1,210	1,220
Asset impairment and mine closure costs	85,520	0
Selling, general and administrative expenses	19,826	22,605
Other operating (income) expense, net	(2,220)	9,086
Total operating expenses	586,518	696,717
Loss from investment in subsidiaries	0	0
Loss from operations	(158,412)	(19,712)
Interest expense, net
Interest expense (contractual interest of $98,565 in 2016)	(44,451)	(99,252)
Interest and investment income	1,138	2,373
Interest expense, net	(43,313)	(96,879)
Nonoperating expense
Expenses related to proposed debt restructuring	(2,213)	0
Reorganization items, net	(3,875)	0
Nonoperating income (expense)	(6,088)	0
Loss before income taxes	(207,813)	(116,591)
Provision for (benefit from) income taxes	(1,111)	(3,396)
Net loss	(206,702)	(113,195)
Total comprehensive income (loss)	(205,842)	(109,591)
Contractual interest	98,565
Parent/Issuer [Member]
Condensed Financial Statements, Captions [Line Items]
Revenues	0	0
Costs, expenses and other
Cost of sales (exclusive of items shown separately below)	2,186	7,470
Depreciation, depletion and amortization	755	1,060
Amortization of acquired sales contracts, net	0	0
Change in fair value of coal derivatives and coal trading activities, net	0	0
Asset impairment and mine closure costs	3,229
Selling, general and administrative expenses	13,540	15,439
Other operating (income) expense, net	(1,098)	3,700
Total operating expenses	18,612	27,669
Loss from investment in subsidiaries	(123,988)	21,050
Loss from operations	(142,600)	(6,619)
Interest expense, net
Interest expense (contractual interest of $98,565 in 2016)	(66,239)	(118,056)
Interest and investment income	7,110	8,072
Interest expense, net	(59,129)	(109,984)
Nonoperating expense
Expenses related to proposed debt restructuring	(2,213)
Reorganization items, net	(3,875)
Nonoperating income (expense)	(6,088)
Loss before income taxes	(207,817)	(116,603)
Provision for (benefit from) income taxes	(1,115)	(3,408)
Net loss	(206,702)	(113,195)
Total comprehensive income (loss)	(205,842)	(109,591)
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Revenues	428,106	677,005
Costs, expenses and other
Cost of sales (exclusive of items shown separately below)	417,677	555,686
Depreciation, depletion and amortization	62,944	103,812
Amortization of acquired sales contracts, net	(833)	(3,390)
Change in fair value of coal derivatives and coal trading activities, net	1,210	1,220
Asset impairment and mine closure costs	82,291
Selling, general and administrative expenses	5,382	6,243
Other operating (income) expense, net	(1,151)	5,278
Total operating expenses	567,520	668,849
Loss from investment in subsidiaries	0	0
Loss from operations	(139,414)	8,156
Interest expense, net
Interest expense (contractual interest of $98,565 in 2016)	(6,365)	(6,763)
Interest and investment income	23,292	19,774
Interest expense, net	16,927	13,011
Nonoperating expense
Expenses related to proposed debt restructuring	0
Reorganization items, net	0
Nonoperating income (expense)	0
Loss before income taxes	(122,487)	21,167
Provision for (benefit from) income taxes	0	0
Net loss	(122,487)	21,167
Total comprehensive income (loss)	(123,489)	24,407
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Revenues	0	0
Costs, expenses and other
Cost of sales (exclusive of items shown separately below)	0	0
Depreciation, depletion and amortization	0	2
Amortization of acquired sales contracts, net	0	0
Change in fair value of coal derivatives and coal trading activities, net	0	0
Asset impairment and mine closure costs	0
Selling, general and administrative expenses	1,272	1,448
Other operating (income) expense, net	(886)	(1,251)
Total operating expenses	386	199
Loss from investment in subsidiaries	0	0
Loss from operations	(386)	(199)
Interest expense, net
Interest expense (contractual interest of $98,565 in 2016)	(2,229)	(1,275)
Interest and investment income	1,118	1,369
Interest expense, net	(1,111)	94
Nonoperating expense
Expenses related to proposed debt restructuring	0
Reorganization items, net	0
Nonoperating income (expense)	0
Loss before income taxes	(1,497)	(105)
Provision for (benefit from) income taxes	4	12
Net loss	(1,501)	(117)
Total comprehensive income (loss)	(1,501)	(117)
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Revenues	0	0
Costs, expenses and other
Cost of sales (exclusive of items shown separately below)	(547)	(834)
Depreciation, depletion and amortization	0	0
Amortization of acquired sales contracts, net	0	0
Change in fair value of coal derivatives and coal trading activities, net	0	0
Asset impairment and mine closure costs	0
Selling, general and administrative expenses	(368)	(525)
Other operating (income) expense, net	915	1,359
Total operating expenses	0	0
Loss from investment in subsidiaries	123,988	(21,050)
Loss from operations	123,988	(21,050)
Interest expense, net
Interest expense (contractual interest of $98,565 in 2016)	30,382	26,842
Interest and investment income	(30,382)	(26,842)
Interest expense, net	0	0
Nonoperating expense
Expenses related to proposed debt restructuring	0
Reorganization items, net	0
Nonoperating income (expense)	0
Loss before income taxes	123,988	(21,050)
Provision for (benefit from) income taxes	0	0
Net loss	123,988	(21,050)
Total comprehensive income (loss)	$ 124,990	$ (24,290)