Condensed Consolidating Financial Information (Condensed Consolidating Balance Sheets) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011	Dec. 31, 2010
Cash and cash equivalents	$ 18,560	$ 15,627	$ 13,293	$ 16,055
Restricted cash	127,074
Accounts receivable	297,773	341,915
Inventories	30,630	46,234
Other current assets	372,710	574,502
Total current assets	846,747	978,278
Property and equipment	12,506,903	11,060,819
Less: Accumulated depreciation, depletion and amortization	(6,414,955)	(4,415,339)
Total property and equipment, net	6,091,948	6,645,480
Other assets	134,256	279,139
TOTAL ASSETS	7,072,951	7,902,897	7,214,107
Accounts payable	519,780	575,327
Other current liabilities	241,385	309,586
Total current liabilities	761,165	884,913
Long-term debt	1,695,342	1,342,100
Deferred income taxes	1,203,703	1,586,798
Other liabilities	159,462	119,782
Total liabilities	3,819,672	3,933,593
Total Equity	3,253,279	3,969,304
TOTAL LIABILITIES AND EQUITY	7,072,951	7,902,897
Parent [Member]
Cash and cash equivalents	16,961	14,711	11,842	8,381
Restricted cash	127,074
Accounts receivable	3,269	2,914
Other current assets	6,472	6,087
Total current assets	153,776	23,712
Intercompany receivables	2,205,219	2,053,132
Property and equipment	210,717	180,300
Less: Accumulated depreciation, depletion and amortization	(73,829)	(57,254)
Total property and equipment, net	136,888	123,046
Investments in subsidiaries (equity method)	2,521,938	3,256,195
Other assets	35,276	28,641
TOTAL ASSETS	5,053,097	5,484,726
Accounts payable	133,968	205,341
Other current liabilities	6,962	5,912
Total current liabilities	140,930	211,253
Long-term debt	1,695,342	1,342,100
Deferred income taxes	(96,550)	(97,045)
Other liabilities	60,096	59,114
Total liabilities	1,799,818	1,515,422
Total Equity	3,253,279	3,969,304
TOTAL LIABILITIES AND EQUITY	5,053,097	5,484,726
Guarantors [Member]
Cash and cash equivalents	1,365		1,451	7,631
Restricted cash
Accounts receivable	271,542	309,038
Inventories	29,672	45,260
Other current assets	355,779	563,635
Total current assets	658,358	917,933
Intercompany receivables	34	53
Property and equipment	11,058,390	9,731,944
Less: Accumulated depreciation, depletion and amortization	(6,168,742)	(4,220,205)
Total property and equipment, net	4,889,648	5,511,739
Other assets	80,783	227,152
TOTAL ASSETS	5,628,823	6,656,877
Accounts payable	352,240	332,710
Other current liabilities	232,336	301,170
Total current liabilities	584,576	633,880
Intercompany payables	2,003,287	1,628,750
Deferred income taxes	984,116	1,442,576
Other liabilities	93,475	54,826
Total liabilities	3,665,454	3,760,032
Total Equity	1,963,369	2,896,845
TOTAL LIABILITIES AND EQUITY	5,628,823	6,656,877
Non-Guarantors [Member]
Cash and cash equivalents	234	916		43
Restricted cash
Accounts receivable	22,962	29,963
Inventories	958	974
Other current assets	10,459	4,780
Total current assets	34,613	36,633
Intercompany receivables	25,142	23,517
Property and equipment	1,237,796	1,148,575
Less: Accumulated depreciation, depletion and amortization	(172,384)	(137,880)
Total property and equipment, net	1,065,412	1,010,695
Other assets	18,197	23,346
TOTAL ASSETS	1,143,364	1,094,191
Accounts payable	33,572	37,276
Other current liabilities	2,087	2,504
Total current liabilities	35,659	39,780
Intercompany payables	227,108	447,952
Deferred income taxes	316,137	241,267
Other liabilities	5,891	5,842
Total liabilities	584,795	734,841
Total Equity	558,569	359,350
TOTAL LIABILITIES AND EQUITY	1,143,364	1,094,191
Eliminations [Member]
Restricted cash
Intercompany receivables	(2,230,395)	(2,076,702)
Investments in subsidiaries (equity method)	(2,521,938)	(3,256,195)
TOTAL ASSETS	(4,752,333)	(5,332,897)
Intercompany payables	(2,230,395)	(2,076,702)
Total liabilities	(2,230,395)	(2,076,702)
Total Equity	(2,521,938)	(3,256,195)
TOTAL LIABILITIES AND EQUITY	$ (4,752,333)	$ (5,332,897)