CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 216,682	$ 224,915
Accounts receivable, net of allowance for credit losses of $10,838 and $10,842 at June 30, 2021 and December 31, 2020, respectively	196,654	160,214
Federal and state income taxes receivable	72	4,428
Inventory	33,763	33,085
Other	60,929	55,314
Total current assets	508,100	477,956
Property and equipment, net	2,511,977	2,761,041
Right of use asset	16,312	16,850
Intangible assets	24,057	30,087
Deposits on equipment purchases	1,599	1,716
Other	11,261	11,419
Total assets	3,073,306	3,299,069
Current liabilities:
Accounts payable	120,853	91,622
Accrued liabilities	166,295	175,004
Lease liability	6,334	7,096
Total current liabilities	293,482	273,722
Long-term lease liability	17,150	19,118
Long-term debt, net of debt discount and issuance costs of $6,859 and $7,271 at June 30, 2021 and December 31, 2020, respectively	901,896	901,484
Deferred tax liabilities, net	40,603	77,676
Other	12,458	11,010
Total liabilities	1,265,589	1,283,010
Commitments and contingencies (see Note 9)
Stockholders' equity:
Preferred stock, par value $0.01; authorized 1,000,000 shares, no shares issued
Common stock, par value $0.01; authorized 400,000,000 shares with 272,835,137 and 271,028,688 issued and 189,004,150 and 187,626,366 outstanding at June 30, 2021 and December 31, 2020, respectively	2,728	2,710
Additional paid-in capital	2,914,043	2,902,236
Retained earnings	254,696	472,014
Accumulated other comprehensive income	6,085	5,412
Treasury stock, at cost, 83,830,987 and 83,402,322 shares at June 30, 2021 and December 31, 2020, respectively	(1,369,835)	(1,366,313)
Total stockholders' equity	1,807,717	2,016,059
Total liabilities and stockholders' equity	$ 3,073,306	$ 3,299,069