Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 583,794	$ 546,465
Accounts receivable - Trade, net of allowance for uncollectible accounts of $4,844 and $4,067, respectively	198,046	238,781
Unbilled revenue	33,928	24,338
Costs in excess of billing	15,671	13,037
Other current assets	131,897	121,621
Total current assets	963,336	944,242
Property and equipment	4,378,185	4,391,064
Less accumulated depreciation	(1,946,358)	(2,059,737)
Property and equipment, net	2,431,827	2,331,327
Other assets:
Equity investments	169,318	175,656
Goodwill	62,769	62,215
Other assets, net	84,707	68,907
Total assets	3,711,957	3,582,347
Current liabilities:
Accounts payable	164,110	147,043
Accrued liabilities	196,289	239,963
Income taxes payable		1,293
Current maturities of long-term debt	13,120	7,877
Total current liabilities	373,519	396,176
Long-term debt	1,159,958	1,147,444
Deferred tax liabilities	455,266	417,610
Asset retirement obligations	136,293	161,208
Other long-term liabilities	8,336	9,368
Total liabilities	2,133,372	2,131,806
Convertible preferred stock	1,000	1,000
Commitments and contingencies
Shareholders' equity:
Common stock, no par, 240,000 shares authorized, 105,333 and 105,530 shares issued, respectively	929,397	908,776
Retained earnings	647,877	522,644
Accumulated other comprehensive loss	(25,956)	(10,017)
Total controlling interest shareholders' equity	1,551,318	1,421,403
Noncontrolling interests	26,267	28,138
Total equity	1,577,585	1,449,541
Total liabilities and shareholders' equity	$ 3,711,957	$ 3,582,347