Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 620,449	$ 546,465
Accounts receivable - Trade, net of allowance for uncollectible accounts of $4,067	237,417	238,781
Unbilled revenue	15,458	24,338
Costs in excess of billing	9,118	13,037
Other current assets	109,669	121,621
Total current assets	992,111	944,242
Property and equipment	4,403,092	4,391,064
Less - accumulated depreciation	(2,041,405)	(2,059,737)
Property and equipment, net	2,361,687	2,331,327
Other assets:
Equity investments	173,440	175,656
Goodwill	62,667	62,215
Other assets, net	75,038	68,907
Total assets	3,664,943	3,582,347
Current liabilities:
Accounts payable	145,631	147,043
Accrued liabilities	196,814	239,963
Income taxes payable	24,977	1,293
Current maturities of long-term debt	12,997	7,877
Total current liabilities	380,419	396,176
Long-term debt	1,167,486	1,147,444
Deferred income taxes	423,098	417,610
Asset retirement obligations	146,696	161,208
Other long-term liabilities	16,516	9,368
Total liabilities	2,134,215	2,131,806
Convertible preferred stock	1,000	1,000
Commitments and contingencies
Shareholders' equity:
Common stock, no par, 240,000 shares authorized, 105,636 and 105,530 shares issued, respectively	932,097	908,776
Retained earnings	588,371	522,644
Accumulated other comprehensive loss	(19,667)	(10,017)
Total controlling interest shareholders' equity	1,500,801	1,421,403
Noncontrolling interests	28,927	28,138
Total equity	1,529,728	1,449,541
Total liabilities and shareholders' equity	$ 3,664,943	$ 3,582,347