Additional Balance Sheet Information (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Accounts receivable, net
Trade accounts	$ 285,367	$ 215,301
Other accounts	381	462
Accounts receivable, gross	285,748	215,763
Allowance for doubtful accounts	(1,039)	(1,039)
Accounts receivable, net	284,709	214,724
Other assets
Deferred compensation plan	25,737	22,510
Debt issuance costs	5,329	6,875
Operating lease right-of-use assets	30,961	33,741
Other accounts	33	85
Other assets	62,060	63,211
Accounts payable
Trade accounts	24,124	12,896
Royalty and other owners	45,900	37,243
Accrued transportation	53,800	52,238
Accrued capital costs	39,771	37,872
Taxes other than income	16,401	13,736
Other accounts	47,196	8,096
Accounts payable	227,192	162,081
Accrued liabilities
Employee benefits	12,762	14,270
Taxes other than income	3,330	3,026
Operating lease liabilities	3,814	3,991
Other accounts	1,135	1,087
Accrued liabilities	21,041	22,374
Other liabilities
Deferred compensation plan	36,525	30,581
Derivative instruments	1,237	0
Operating lease liabilities	27,035	29,628
Other accounts	12,731	21,069
Other liabilities	$ 77,528	$ 81,278