Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 279,459	$ 266,592
Accounts receivable:
Trade, net of allowance for uncollectible accounts of $0 and $2,752, respectively	67,932	113,336
Unbilled and other	51,943	29,947
Other current assets	51,594	41,768
Total current assets	450,928	451,643
Property and equipment	2,785,778	2,695,772
Less accumulated depreciation	(959,033)	(889,783)
Property and equipment, net	1,826,745	1,805,989
Other assets, net	70,057	105,205
Total assets	2,347,730	2,362,837
Current liabilities:
Accounts payable	54,813	81,299
Accrued liabilities	85,594	71,680
Income tax payable	3,829	2,799
Current maturities of long-term debt	47,252	109,861
Total current liabilities	191,488	265,639
Long-term debt	393,063	385,766
Deferred tax liabilities	105,862	103,349
Other non-current liabilities	39,538	40,690
Total liabilities	729,951	795,444
Shareholders’ equity:
Common stock, no par, 240,000 shares authorized, 148,203 and 147,740 shares issued, respectively	1,308,709	1,284,274
Retained earnings	383,034	352,906
Accumulated other comprehensive loss	(73,964)	(69,787)
Total shareholders’ equity	1,617,779	1,567,393
Total liabilities and shareholders’ equity	$ 2,347,730	$ 2,362,837