Additional Balance Sheet Information (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Accounts receivable, net
Trade accounts	$ 135,862	$ 209,200
Other accounts	881	1,007
Accounts receivable, gross	136,743	210,207
Allowance for doubtful accounts	(1,046)	(1,184)
Accounts receivable, net	135,697	209,023
Other assets
Deferred compensation plan	15,784	18,381
Debt issuance costs	8,422	8,938
Operating lease right-of-use assets	35,629	35,916
Other accounts	54	56
Other assets	59,889	63,291
Accounts payable
Trade accounts	25,520	21,663
Royalty and other owners	24,393	36,191
Accrued transportation	51,848	55,586
Accrued capital costs	51,883	40,337
Taxes other than income	20,517	16,971
Other accounts	9,655	19,063
Accounts payable	183,816	189,811
Accrued liabilities
Employee benefits	13,177	22,727
Taxes other than income	3,308	3,850
Operating lease liabilities	3,443	3,124
Other accounts	1,481	1,589
Accrued liabilities	21,409	31,290
Other liabilities
Deferred compensation plan	24,306	27,012
Operating lease liabilities	32,079	32,677
Other accounts	8,691	8,595
Other liabilities	$ 65,076	$ 68,284