Sales of Assets (Details) $ in Thousands	1 Months Ended												6 Months Ended	12 Months Ended
	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jul. 31, 2016 USD ($)	Jun. 30, 2016 USD ($)	Apr. 30, 2016 USD ($)	Feb. 29, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Sep. 30, 2014 USD ($) a	Mar. 31, 2014 USD ($)	Feb. 28, 2014 USD ($)	Jun. 30, 2015 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Sale Of Assets [Line Items]
Net proceeds from sale of interest in wells and related leasehold interest										$ 29,300	$ 71,000
Sale of oil and gas, term assignment							3 years
Threshold percent of net revenue							75.00%		75.00%
Proceeds from sale of assets														$ 423,905	$ 71,460	$ 104,529
Gas and oil area sold | a										7,500
Escrow deposits related to property sales											$ 6,800
Proceeds from sale of property												$ 5,100
OKLAHOMA
Sale Of Assets [Line Items]
Net proceeds from sale of interest in wells and related leasehold interest				$ 1,500
Giddings Area, TX
Sale Of Assets [Line Items]
Net proceeds from sale of interest in wells and related leasehold interest	$ 400,000
Glasscock County, TX
Sale Of Assets [Line Items]
Net proceeds from sale of interest in wells and related leasehold interest			$ 19,400
Burleson County, TX
Sale Of Assets [Line Items]
Net proceeds from sale of interest in wells and related leasehold interest		$ 1,400			$ 2,000	$ 800	$ 21,800		$ 22,100
South Louisiana
Sale Of Assets [Line Items]
Proceeds from sale of assets								$ 11,800
Wells and Related Equipment and Facilities
Sale Of Assets [Line Items]
Net proceeds from sale of interest in wells and related leasehold interest													$ 7,300