Condensed Consolidating Financial Information (Condensed Consolidating Balance Sheets) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Cash and cash equivalents	$ 15,627	$ 16,055	$ 13,184	$ 196,277
Accounts receivable	341,915	351,573
Inventories	46,234	35,098
Other current assets	574,502	178,167
Total current assets	978,278	580,893
Intercompany receivables	0	0
Investments		0
Property and equipment	11,060,819	8,980,885
Less: Accumulated depreciation, depletion and amortization	4,415,339	3,682,688
Property and equipment, net	6,645,480	5,298,197
Investments in subsidiaries (equity method)	0	0
Other assets	279,139	138,373
TOTAL ASSETS	7,902,897	6,017,463	4,770,250
Accounts and notes payable	576,527	545,095
Other current liabilities	308,386	148,888
Total current liabilities	884,913	693,983
Intercompany payables	0	0
Long-term debt	1,342,100	1,093,000
Deferred income taxes	1,586,798	1,130,292
Other liabilities	119,782	135,312
Total liabilities	3,933,593	3,052,587
Commitments and Contingencies
Total Equity	3,969,304	2,964,876	2,340,981	2,517,963
TOTAL LIABILITIES AND EQUITY	7,902,897	6,017,463
Parent [Member]
Cash and cash equivalents	14,711	8,381	7,378	195,969
Accounts receivable	2,914	382
Inventories	0	0
Other current assets	6,087	5,015
Total current assets	23,712	13,778
Intercompany receivables	2,053,132	1,820,857
Investments		0
Property and equipment	180,300	124,823
Less: Accumulated depreciation, depletion and amortization	57,254	52,256
Property and equipment, net	123,046	72,567
Investments in subsidiaries (equity method)	3,256,195	2,253,871
Other assets	28,641	18,918
TOTAL ASSETS	5,484,726	4,179,991
Accounts and notes payable	206,541	175,476
Other current liabilities	4,712	3,288
Total current liabilities	211,253	178,764
Intercompany payables	0	0
Long-term debt	1,342,100	1,093,000
Deferred income taxes	(97,045)	(98,206)
Other liabilities	59,114	41,557
Total liabilities	1,515,422	1,215,115
Total Equity	3,969,304	2,964,876
TOTAL LIABILITIES AND EQUITY	5,484,726	4,179,991
Guarantors [Member]
Cash and cash equivalents	0	7,631	5,776	0
Accounts receivable	309,038	331,154
Inventories	45,260	34,263
Other current assets	563,635	171,060
Total current assets	917,933	544,108
Intercompany receivables	53	131
Investments		11,103
Property and equipment	9,731,944	7,871,279
Less: Accumulated depreciation, depletion and amortization	4,220,205	3,526,010
Property and equipment, net	5,511,739	4,345,269
Investments in subsidiaries (equity method)	0	0
Other assets	227,152	92,747
TOTAL ASSETS	6,656,877	4,993,358
Accounts and notes payable	332,710	336,411
Other current liabilities	301,170	142,839
Total current liabilities	633,880	479,250
Intercompany payables	1,628,750	1,317,696
Long-term debt	0	0
Deferred income taxes	1,442,576	1,066,166
Other liabilities	54,826	89,986
Total liabilities	3,760,032	2,953,098
Total Equity	2,896,845	2,040,260
TOTAL LIABILITIES AND EQUITY	6,656,877	4,993,358
Non-Guarantors [Member]
Cash and cash equivalents	916	43	30	308
Accounts receivable	29,963	20,037
Inventories	974	835
Other current assets	4,780	2,092
Total current assets	36,633	23,007
Intercompany receivables	23,517	18,724
Investments		(11,102)
Property and equipment	1,148,575	984,783
Less: Accumulated depreciation, depletion and amortization	137,880	104,422
Property and equipment, net	1,010,695	880,361
Investments in subsidiaries (equity method)	0	0
Other assets	23,346	26,708
TOTAL ASSETS	1,094,191	937,698
Accounts and notes payable	37,276	33,208
Other current liabilities	2,504	2,761
Total current liabilities	39,780	35,969
Intercompany payables	447,952	522,017
Long-term debt	0	0
Deferred income taxes	241,267	162,332
Other liabilities	5,842	3,769
Total liabilities	734,841	724,087
Total Equity	359,350	213,611
TOTAL LIABILITIES AND EQUITY	1,094,191	937,698
Eliminations [Member]
Cash and cash equivalents	0	0	0	0
Accounts receivable	0	0
Inventories	0	0
Other current assets	0	0
Total current assets	0	0
Intercompany receivables	(2,076,702)	(1,839,712)
Investments		(1)
Property and equipment	0	0
Less: Accumulated depreciation, depletion and amortization	0	0
Property and equipment, net	0	0
Investments in subsidiaries (equity method)	(3,256,195)	(2,253,871)
Other assets	0	0
TOTAL ASSETS	(5,332,897)	(4,093,584)
Accounts and notes payable	0	0
Other current liabilities	0	0
Total current liabilities	0	0
Intercompany payables	(2,076,702)	(1,839,713)
Long-term debt	0	0
Deferred income taxes	0	0
Other liabilities	0	0
Total liabilities	(2,076,702)	(1,839,713)
Total Equity	(3,256,195)	(2,253,871)
TOTAL LIABILITIES AND EQUITY	$ (5,332,897)	$ (4,093,584)