Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 470,079	$ 478,200
Accounts receivable:
Trade, net of allowance for uncollectible accounts of $1,371 and $2,234, respectively	132,219	156,925
Unbilled revenue	55,999	25,732
Costs in excess of billing	1,508	1,508
Income tax receivable, net	25,956
Current deferred tax assets	19,865	51,573
Other current assets	46,759	29,709
Total current assets	752,385	743,647
Property and equipment	1,966,500	1,963,706
Less accumulated depreciation	(444,881)	(431,489)
Property and equipment, net	1,521,619	1,532,217
Other assets:
Equity investments	155,730	157,919
Goodwill	63,336	63,230
Other assets, net	66,925	47,267
Total assets	2,559,995	2,544,280
Current liabilities:
Accounts payable	96,370	72,602
Accrued liabilities	59,814	96,482
Income tax payable		760
Current maturities of long-term debt	20,508	20,376
Total current liabilities	176,692	190,220
Long-term debt	540,636	545,776
Deferred tax liabilities	270,918	265,879
Other non-current liabilities	13,748	18,295
Total liabilities	1,001,994	1,020,170
Commitments and contingencies
Shareholders' equity:
Common stock, no par, 240,000 shares authorized, 105,532 and 105,640 shares issued, respectively	934,328	933,507
Retained earnings	639,951	586,232
Accumulated other comprehensive loss	(16,278)	(20,688)
Total controlling interest shareholders' equity	1,558,001	1,499,051
Noncontrolling interests		25,059
Total equity	1,558,001	1,524,110
Total liabilities and shareholders' equity	$ 2,559,995	$ 2,544,280