Additional Balance Sheet Information - Schedule of Additional Balance Sheet Information (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Accounts receivable, net
Trade accounts	$ 175,384	$ 215,511
Joint interest accounts	1,551	467
Other accounts	4,896	1,312
Accounts receivable, gross	181,831	217,290
Allowance for doubtful accounts	(1,286)	(1,286)
Accounts receivable, net	180,545	216,004
Other assets
Deferred compensation plan	16,050	14,966
Debt issuance costs	6,281	7,990
Income taxes receivable	3,047	0
Other accounts	202	56
Other assets	25,580	23,012
Accounts payable
Trade accounts	33,900	7,815
Natural gas purchases	27,852	4,299
Royalty and other owners	28,743	39,207
Accrued transportation	40,031	51,433
Accrued capital costs	24,854	31,130
Taxes other than income	9,426	16,801
Deposits received for asset sales	5,000	81,500
Other accounts	66,172	5,860
Accounts payable	235,978	238,045
Accrued liabilities
Employee benefits	11,113	20,645
Taxes other than income	1,562	550
Asset retirement obligations	1,000	4,952
Other accounts	142	1,294
Accrued liabilities	13,817	27,441
Other liabilities
Deferred compensation plan	27,849	29,145
Other accounts	32,699	10,578
Other liabilities	$ 60,548	$ 39,723