Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Current assets:
Cash and cash equivalents	$ 546,465	$ 391,085
Accounts receivable - Trade, net of allowance for uncollectible accounts of $4,067 and $4,527	238,781	177,293
Unbilled revenue	24,338	33,712
Costs in excess of billing	13,037	15,699
Other current assets	121,621	123,065
Total current assets	944,242	740,854
Property and equipment	4,391,064	4,486,077
Less - Accumulated depreciation	(2,059,737)	(1,958,997)
Property and equipment, net	2,331,327	2,527,080
Other assets:
Equity investments	175,656	187,031
Goodwill, net	62,215	62,494
Other assets, net	68,907	74,561
Total assets	3,582,347	3,592,020
Current liabilities:
Accounts payable	147,043	159,381
Accrued liabilities	239,963	198,237
Income tax payable	1,293
Current maturities of long-term debt	7,877	10,179
Total current liabilities	396,176	367,797
Long-term debt	1,147,444	1,347,753
Deferred income taxes	417,610	413,639
Asset retirement obligations	161,208	170,410
Other long-term liabilities	9,368	5,777
Total liabilities	2,131,806	2,305,376
Convertible preferred stock	1,000	1,000
Commitments and contingencies
Shareholders' equity:
Common stock, no par, 240,000 shares authorized, 105,530 and 105,592 shares issued	908,776	906,957
Retained earnings	522,644	392,705
Accumulated other comprehensive loss	(10,017)	(39,058)
Total controlling interest shareholders' equity	1,421,403	1,260,604
Noncontrolling interests	28,138	25,040
Total equity	1,449,541	1,285,644
Total liabilities and shareholders' equity	$ 3,582,347	$ 3,592,020