Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Revenues:
Total revenues	$ 184,799	$ 329,546	$ 672,352	$ 1,121,782
Segment operating income (loss):
Total operating loss	(106,117)	(54,833)	(3,214,114)	(201,334)
Interest expense, net	(42,222)	(79,231)	(195,309)	(218,065)
Gain on extinguishment of debt	0	3,394	58,626	902
Other income, net	0	1,424	0	646
Loss before reorganization items, net and income tax benefit	(148,339)	(129,246)	(3,350,797)	(417,851)
Reorganization items, net	(17,017)	0	(17,017)	0
Loss before income tax benefit	(165,356)	(129,246)	(3,367,814)	(417,851)
Income tax benefit	(6,713)	(30,344)	(673,911)	(75,380)
Net loss	(158,643)	(98,902)	(2,693,903)	(342,471)
Depreciation and depletion:
Total depreciation and depletion	43,487	58,413	154,147	204,653
Capital expenditures:
Total capital expenditures	12,997	26,257	61,329	69,733
Segment assets:
Total segment assets	1,976,919		1,976,919		$ 5,331,364
U.S. Operations
Segment operating income (loss):
Income tax benefit	(2,000)
Canadian and U.K. Operations
Segment operating income (loss):
Income tax benefit	(3,300)
Operating segment | U.S. Operations
Revenues:
Total revenues	160,215	282,356	599,537	911,705
Segment operating income (loss):
Total operating loss	(90,422)	(26,837)	(215,348)	(51,376)
Depreciation and depletion:
Total depreciation and depletion	34,163	36,649	106,228	113,409
Capital expenditures:
Total capital expenditures	12,556	23,503	58,929	63,244
Segment assets:
Total segment assets	1,051,087		1,051,087		1,132,095
Operating segment | Canadian and U.K. Operations
Revenues:
Total revenues	24,280	46,355	70,780	206,976
Segment operating income (loss):
Total operating loss	(11,451)	(26,598)	(2,974,547)	(145,642)
Depreciation and depletion:
Total depreciation and depletion	8,831	21,152	46,252	89,371
Capital expenditures:
Total capital expenditures	340	1,687	1,701	3,731
Segment assets:
Total segment assets	573,111		573,111		3,541,015
Other
Revenues:
Total revenues	304	835	2,035	3,101
Segment operating income (loss):
Total operating loss	(4,244)	(1,398)	(24,219)	(4,316)
Depreciation and depletion:
Total depreciation and depletion	493	612	1,667	1,873
Capital expenditures:
Total capital expenditures	101	$ 1,067	699	$ 2,758
Segment assets:
Total segment assets	$ 352,721		$ 352,721		$ 658,254