CONDENSED CONSOLIDATED BALANCE SHEET (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets
Cash and cash equivalents	$ 76,270	$ 140,113
Restricted cash	9,981	11,578
Accounts receivable, net	284,709	214,724
Income taxes receivable	55,728	6,171
Inventories	12,781	15,270
Derivative instruments	0	26,209
Other current assets	3,254	1,650
Total current assets	442,723	415,715
Properties and equipment, net (Successful efforts method)	4,225,914	4,044,606
Other assets	62,060	63,211
TOTAL ASSETS	4,730,697	4,523,532
Current liabilities
Accounts payable	227,192	162,081
Current portion of long-term debt	0	188,000
Accrued liabilities	21,041	22,374
Interest payable	4,883	17,771
Derivative instruments	212,894	0
Total current liabilities	466,010	390,226
Long-term debt, net	946,509	945,924
Deferred income taxes	790,604	774,195
Asset retirement obligations	91,732	85,489
Postretirement benefits	32,202	30,713
Other liabilities	77,528	81,278
Total liabilities	2,404,585	2,307,825
Commitments and contingencies
Stockholders' equity
Common stock	47,862	47,783
Additional paid-in capital	1,823,373	1,804,354
Retained earnings	2,276,071	2,184,352
Accumulated other comprehensive income	2,007	2,419
Treasury stock	(1,823,201)	(1,823,201)
Total stockholders' equity	2,326,112	2,215,707
Total liabilities and stockholders' equity	$ 4,730,697	$ 4,523,532