Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 261,142	$ 279,459
Accounts receivable:
Trade, net of allowance for uncollectible accounts of $0	79,916	67,932
Unbilled and other	71,115	51,943
Other current assets	77,764	51,594
Total current assets	489,937	450,928
Property and equipment	2,805,043	2,785,778
Less accumulated depreciation	(1,000,679)	(959,033)
Property and equipment, net	1,804,364	1,826,745
Operating lease right-of-use assets	227,213	0
Other assets, net	98,708	70,057
Total assets	2,620,222	2,347,730
Current liabilities:
Accounts payable	76,536	54,813
Accrued liabilities	84,611	85,594
Income tax payable	0	3,829
Current maturities of long-term debt	117,033	47,252
Current operating lease liabilities	54,449	0
Total current liabilities	332,629	191,488
Long-term debt	307,455	393,063
Operating lease liabilities	178,731	0
Deferred tax liabilities	108,344	105,862
Other non-current liabilities	41,284	39,538
Total liabilities	968,443	729,951
Redeemable noncontrolling interests	3,383	0
Shareholders’ equity:
Common stock, no par, 240,000 shares authorized, 148,759 and 148,203 shares issued, respectively	1,314,163	1,308,709
Retained earnings	405,748	383,034
Accumulated other comprehensive loss	(71,515)	(73,964)
Total shareholders’ equity	1,648,396	1,617,779
Total liabilities, redeemable noncontrolling interests and shareholders’ equity	$ 2,620,222	$ 2,347,730