Asset Impairment - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment	$ 220,025	$ 6,583
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	$ 208,300	4,300
Permian Basin unproved leasehold properties
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment	4,135	2,005
San Juan Basin
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment	7,519	0
San Juan Basin unproved leasehold properties
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment	$ 40	$ 248