Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 488,184	$ 494,192
Accounts receivable:
Trade, net of allowance for uncollectible accounts of $350	57,804	76,287
Unbilled revenue and other	6,637	20,465
Current deferred tax assets	53,027	53,573
Other current assets	41,594	39,518
Total current assets	647,246	684,035
Property and equipment	2,551,363	2,544,857
Less accumulated depreciation	(964,492)	(941,848)
Property and equipment, net	1,586,871	1,603,009
Other assets:
Equity investments	0	26,200
Goodwill	45,107	45,107
Other assets, net	35,163	41,608
Total assets	2,314,387	2,399,959
Current liabilities:
Accounts payable	41,369	65,370
Accrued liabilities	67,265	71,641
Income tax payable	369	2,261
Current maturities of long-term debt	71,786	71,640
Total current liabilities	180,789	210,912
Long-term debt	659,948	677,695
Deferred tax liabilities	174,064	180,974
Other non-current liabilities	49,845	51,415
Total liabilities	$ 1,064,646	$ 1,120,996
Commitments and contingencies
Shareholders’ equity:
Common stock, no par, 240,000 shares authorized, 107,514 and 106,289 shares issued, respectively	$ 945,952	$ 945,565
Retained earnings	376,476	404,299
Accumulated other comprehensive loss	(72,687)	(70,901)
Total shareholders’ equity	1,249,741	1,278,963
Total liabilities and shareholders’ equity	$ 2,314,387	$ 2,399,959