Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 220,023	$ 279,459
Accounts receivable:
Trade, net of allowance for uncollectible accounts of $0	102,072	67,932
Unbilled and other	41,364	51,943
Other current assets	87,184	51,594
Total current assets	450,643	450,928
Property and equipment	2,804,271	2,785,778
Less accumulated depreciation	(986,202)	(959,033)
Property and equipment, net	1,818,069	1,826,745
Operating lease right-of-use assets	240,332	0
Other assets, net	98,277	70,057
Total assets	2,607,321	2,347,730
Current liabilities:
Accounts payable	63,849	54,813
Accrued liabilities	81,842	85,594
Income tax payable	0	3,829
Current maturities of long-term debt	47,888	47,252
Current operating lease liabilities	55,241	0
Total current liabilities	248,820	191,488
Long-term debt	381,319	393,063
Operating lease liabilities	191,545	0
Deferred tax liabilities	107,367	105,862
Other non-current liabilities	48,427	39,538
Total liabilities	977,478	729,951
Shareholders’ equity:
Common stock, no par, 240,000 shares authorized, 148,785 and 148,203 shares issued, respectively	1,310,738	1,308,709
Retained earnings	388,912	383,034
Accumulated other comprehensive loss	(69,807)	(73,964)
Total shareholders’ equity	1,629,843	1,617,779
Total liabilities and shareholders’ equity	$ 2,607,321	$ 2,347,730