Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 501,457	$ 478,200
Accounts receivable:
Trade, net of allowance for uncollectible accounts of $5,971 and $2,234, respectively	189,445	156,925
Unbilled revenue	35,797	25,732
Costs in excess of billing	1,508	1,508
Income tax receivable, net	23,771
Current deferred tax assets	24,370	51,573
Other current assets	41,917	29,709
Total current assets	818,265	743,647
Property and equipment	2,072,116	1,963,706
Less accumulated depreciation	(467,928)	(431,489)
Property and equipment, net	1,604,188	1,532,217
Other assets:
Equity investments	152,877	157,919
Goodwill	63,829	63,230
Other assets, net	61,951	47,267
Total assets	2,701,110	2,544,280
Current liabilities:
Accounts payable	157,553	72,602
Accrued liabilities	79,130	96,482
Income tax payable		760
Current maturities of long-term debt	20,508	20,376
Total current liabilities	257,191	190,220
Long-term debt	538,254	545,776
Deferred tax liabilities	272,448	265,879
Other non-current liabilities	11,297	18,295
Total liabilities	1,079,190	1,020,170
Commitments and contingencies
Shareholders' equity:
Common stock, no par, 240,000 shares authorized, 105,535 and 105,640 shares issued, respectively	935,821	933,507
Retained earnings	697,733	586,232
Accumulated other comprehensive loss	(11,634)	(20,688)
Total controlling interest shareholders' equity	1,621,920	1,499,051
Noncontrolling interests		25,059
Total equity	1,621,920	1,524,110
Total liabilities and shareholders' equity	$ 2,701,110	$ 2,544,280