Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Revenues:
Total Revenues	$ 413,885	$ 491,343
Segment operating income (loss):
Total operating loss	(47,062)	(63,620)
Less interest expense, net	(79,321)	(51,968)
Other income (loss)	(1,756)	105
Loss before income tax benefit	(128,139)	(115,483)
Income tax benefit	(35,961)	(66,039)
Net loss	(92,178)	(49,444)
Depreciation and depletion:
Total depreciation and depletion	76,424	81,190
Capital expenditures:
Total capital expenditures	12,281	34,027
Segment assets:
Total Segment assets	5,648,665	5,590,860	5,590,860
Operating segment | U.S. Operations
Revenues:
Total Revenues	330,664	339,225
Segment operating income (loss):
Total operating loss	5,870	(6,957)
Depreciation and depletion:
Total depreciation and depletion	39,066	47,473
Capital expenditures:
Total capital expenditures	10,251	27,401
Segment assets:
Total Segment assets	1,256,363	1,265,255
Operating segment | Canadian and U.K. operations
Revenues:
Total Revenues	81,577	151,444
Segment operating income (loss):
Total operating loss	(52,618)	(48,766)
Depreciation and depletion:
Total depreciation and depletion	36,710	33,232
Capital expenditures:
Total capital expenditures	609	6,314
Segment assets:
Total Segment assets	3,659,940	3,687,925
Other
Revenues:
Total Revenues	1,644	674
Segment operating income (loss):
Total operating loss	(314)	(7,897)
Depreciation and depletion:
Total depreciation and depletion	648	485
Capital expenditures:
Total capital expenditures	1,421	312
Segment assets:
Total Segment assets	$ 732,362	$ 637,680