Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 649,503	$ 546,465
Accounts receivable - Trade, net of allowance for uncollectible accounts of $4,067	187,904	238,781
Unbilled revenue	30,053	24,338
Costs in excess of billing	21,492	13,037
Other current assets	117,979	121,621
Total current assets	1,006,931	944,242
Property and equipment	4,366,783	4,391,064
Less accumulated depreciation	(2,007,490)	(2,059,737)
Property and equipment, net	2,359,293	2,331,327
Other assets:
Equity investments	173,543	175,656
Goodwill	62,252	62,215
Other assets, net	86,786	68,907
Total assets	3,688,805	3,582,347
Current liabilities:
Accounts payable	156,738	147,043
Accrued liabilities	177,225	239,963
Income taxes payable	3,065	1,293
Current maturities of long-term debt	12,997	7,877
Total current liabilities	350,025	396,176
Long-term debt	1,167,908	1,147,444
Deferred tax liabilities	445,817	417,610
Asset retirement obligations	135,235	161,208
Other long-term liabilities	8,832	9,368
Total liabilities	2,107,817	2,131,806
Convertible preferred stock	1,000	1,000
Commitments and contingencies
Shareholders' equity:
Common stock, no par, 240,000 shares authorized, 105,631 and 105,530 shares issued, respectively	927,085	908,776
Retained earnings	633,012	522,644
Accumulated other comprehensive loss	(9,825)	(10,017)
Total controlling interest shareholders' equity	1,550,272	1,421,403
Noncontrolling interests	29,716	28,138
Total equity	1,579,988	1,449,541
Total liabilities and shareholders' equity	$ 3,688,805	$ 3,582,347