Additional Balance Sheet Information - Schedule of Additional Balance Sheet Information (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Accounts receivable, net
Trade accounts	$ 115,463	$ 116,772
Joint interest accounts	1,517	2,013
Other accounts	2,211	2,557
Accounts receivable, net	119,191	121,342
Allowance for doubtful accounts	(1,143)	(1,113)
Accounts receivable, net	118,048	120,229
Inventories
Tubular goods and well equipment	13,038	14,685
Natural gas in storage	1,947	2,364
Inventories	14,985	17,049
Other assets
Deferred compensation plan	11,760	12,921
Debt issuance costs	13,113	14,871
Other accounts	56	64
Other assets	24,929	27,856
Accounts payable
Trade accounts	23,573	30,038
Natural gas purchases	1,446	2,231
Royalty and other owners	73,153	75,106
Accrued capital costs	30,646	27,479
Taxes other than income	6,078	14,628
Other accounts	7,605	10,925
Accounts payable current	142,501	160,407
Accrued liabilities
Employee benefits	6,670	13,870
Taxes other than income	9,299	5,073
Income taxes payable	380	0
Asset retirement obligations	2,000	2,000
Other accounts	995	3,980
Accrued liabilities	19,344	24,923
Other liabilities
Deferred compensation plan	24,522	22,371
Derivative instruments	994	0
Other accounts	3,928	3,653
Other liabilities	$ 29,444	$ 26,024