Asset Impairment - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2016	Mar. 31, 2016	Jun. 30, 2017	Jun. 30, 2016
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment	$ 29		$ 0		$ 1,489	$ 220,025
Price curve, term					5 years
Increase (decrease) in carrying amount of properties, percent					3.00%
Oil
Impaired Long-Lived Assets Held and Used [Line Items]
Increase (decrease) in carrying amount of properties, percent				(5.00%)
Natural Gas
Impaired Long-Lived Assets Held and Used [Line Items]
Increase (decrease) in carrying amount of properties, percent				(4.00%)
Permian Basin
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment		$ 1,100		$ 208,300
Permian Basin unproved leasehold properties
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment	29		0	4,100	$ 393	4,135
San Juan Basin
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment	$ 0		$ 0	$ 7,500	$ 0	$ 7,519