Supplemental Guarantor and Non-Guarantor Financial Information (Income Statement) (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Revenues:
Sales	$ 319,542,000	$ 445,937,000	$ 1,102,753,000	$ 1,373,344,000
Miscellaneous income	10,004,000	9,859,000	19,029,000	15,291,000
Total revenues	329,546,000	455,796,000	1,121,782,000	1,388,635,000
Costs and expenses:
Cost of sales (exclusive of depreciation and depletion)	297,925,000	395,311,000	991,561,000	1,183,861,000
Depreciation and depletion	58,413,000	82,986,000	204,653,000	232,496,000
Selling, general and administrative	16,598,000	21,873,000	56,379,000	79,676,000
Postretirement benefits	13,869,000	14,707,000	41,607,000	44,157,000
Restructuring and asset impairments	(2,426,000)	0	28,916,000	1,699,000
Total costs and expenses	384,379,000	514,877,000	1,323,116,000	1,541,889,000
Operating loss	(54,833,000)	(59,081,000)	(201,334,000)	(153,254,000)
Interest expense, net	(79,231,000)	(58,362,000)	(218,065,000)	(157,314,000)
Gain (loss) on extinguishment of debt	3,394,000	(874,000)	902,000	(6,875,000)
Other income (loss), net	1,424,000	593,000	646,000	(16,000)
Loss before income tax benefit	(129,246,000)	(117,724,000)	(417,851,000)	(317,459,000)
Income tax benefit	(30,344,000)	(17,000,000)	(75,380,000)	(132,799,000)
Equity in net earnings (losses) of subsidiaries	0	0	0	0
Net income (loss)	(98,902,000)	(100,724,000)	(342,471,000)	(184,660,000)
Reportable legal entities | Parent (Issuer)
Revenues:
Sales	0	0	0	0
Miscellaneous income	(40,000)	(932,000)	939,000	(159,000)
Total revenues	(40,000)	(932,000)	939,000	(159,000)
Costs and expenses:
Cost of sales (exclusive of depreciation and depletion)	0	0	0	0
Depreciation and depletion	612,000	543,000	1,873,000	1,539,000
Selling, general and administrative	1,387,000	(3,730,000)	4,501,000	6,420,000
Postretirement benefits	(45,000)	(54,000)	(133,000)	(164,000)
Restructuring and asset impairments	50,000		564,000	0
Total costs and expenses	2,004,000	(3,241,000)	6,805,000	7,795,000
Operating loss	(2,044,000)	2,309,000	(5,866,000)	(7,954,000)
Interest expense, net	(77,856,000)	(65,013,000)	(222,598,000)	(173,640,000)
Gain (loss) on extinguishment of debt	3,394,000	(874,000)	902,000	(6,875,000)
Other income (loss), net	1,424,000	(234,000)	705,000	(234,000)
Loss before income tax benefit	(75,082,000)	(63,812,000)	(226,857,000)	(188,703,000)
Income tax benefit	(404,000)	(715,000)	(2,837,000)	(49,490,000)
Equity in net earnings (losses) of subsidiaries	(24,224,000)	(37,627,000)	(118,451,000)	(45,447,000)
Net income (loss)	(98,902,000)	(100,724,000)	(342,471,000)	(184,660,000)
Reportable legal entities | Guarantor Subsidiaries
Revenues:
Sales	270,176,000	302,328,000	854,074,000	916,338,000
Miscellaneous income	1,818,000	5,669,000	5,512,000	8,638,000
Total revenues	271,994,000	307,997,000	859,586,000	924,976,000
Costs and expenses:
Cost of sales (exclusive of depreciation and depletion)	238,470,000	234,913,000	700,424,000	693,904,000
Depreciation and depletion	32,295,000	43,600,000	99,343,000	117,683,000
Selling, general and administrative	10,868,000	13,854,000	34,739,000	41,108,000
Postretirement benefits	13,914,000	14,761,000	41,740,000	44,321,000
Restructuring and asset impairments	37,000		23,723,000	(8,947,000)
Total costs and expenses	295,584,000	307,128,000	899,969,000	888,069,000
Operating loss	(23,590,000)	869,000	(40,383,000)	36,907,000
Interest expense, net	(257,000)	8,465,000	6,705,000	21,748,000
Gain (loss) on extinguishment of debt	0	0	0	0
Other income (loss), net	0	218,000	0	218,000
Loss before income tax benefit	(23,847,000)	9,552,000	(33,678,000)	58,873,000
Income tax benefit	17,000	1,368,000	(4,342,000)	6,505,000
Equity in net earnings (losses) of subsidiaries	0	0	0	0
Net income (loss)	(23,864,000)	8,184,000	(29,336,000)	52,368,000
Reportable legal entities | Non-Guarantor Subsidiaries
Revenues:
Sales	49,366,000	143,609,000	248,679,000	457,006,000
Miscellaneous income	8,226,000	5,122,000	12,578,000	6,812,000
Total revenues	57,592,000	148,731,000	261,257,000	463,818,000
Costs and expenses:
Cost of sales (exclusive of depreciation and depletion)	59,455,000	160,398,000	291,137,000	489,957,000
Depreciation and depletion	25,506,000	38,843,000	103,437,000	113,274,000
Selling, general and administrative	4,343,000	11,749,000	17,139,000	32,148,000
Postretirement benefits	0	0	0	0
Restructuring and asset impairments	(2,513,000)		4,629,000	10,646,000
Total costs and expenses	86,791,000	210,990,000	416,342,000	646,025,000
Operating loss	(29,199,000)	(62,259,000)	(155,085,000)	(182,207,000)
Interest expense, net	(1,118,000)	(1,814,000)	(2,172,000)	(5,422,000)
Gain (loss) on extinguishment of debt	0	0	0	0
Other income (loss), net	0	609,000	(59,000)	0
Loss before income tax benefit	(30,317,000)	(63,464,000)	(157,316,000)	(187,629,000)
Income tax benefit	(29,957,000)	(17,653,000)	(68,201,000)	(89,814,000)
Equity in net earnings (losses) of subsidiaries	0	0	0	0
Net income (loss)	(360,000)	(45,811,000)	(89,115,000)	(97,815,000)
Eliminations
Revenues:
Sales	0	0	0	0
Miscellaneous income	0	0	0	0
Total revenues	0	0	0	0
Costs and expenses:
Cost of sales (exclusive of depreciation and depletion)	0	0	0	0
Depreciation and depletion	0	0	0	0
Selling, general and administrative	0	0	0	0
Postretirement benefits	0	0	0	0
Restructuring and asset impairments	0		0	0
Total costs and expenses	0	0	0	0
Operating loss	0	0	0	0
Interest expense, net	0	0	0	0
Gain (loss) on extinguishment of debt	0	0	0	0
Other income (loss), net	0	0	0	0
Loss before income tax benefit	0	0	0	0
Income tax benefit	0	0	0	0
Equity in net earnings (losses) of subsidiaries	24,224,000	37,627,000	118,451,000	45,447,000
Net income (loss)	$ 24,224,000	$ 37,627,000	$ 118,451,000	$ 45,447,000