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Properties and Equipment, Net - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended		6 Months Ended
	Jun. 30, 2017	Feb. 29, 2016	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Proceeds from sale of assets					$ 1,475	$ 49,828
Oil and gas properties, net	$ 4,202,985		$ 4,202,985		4,202,985		$ 4,250,125
Asset retirement obligations	57,502		57,502		57,502		$ 131,733
Gain (loss) on sale of assets			$ (1,403)	$ (878)	$ (1,626)	$ 477
West Virginia, Virginia, and Ohio \| Oil and Gas Properties, Proved and Unproved
Property, Plant and Equipment [Line Items]
Proceeds from sale of assets	41,300
Impairment of oil and gas properties	$ 68,600
East Texas \| Oil and Gas Properties, Proved and Unproved
Property, Plant and Equipment [Line Items]
Proceeds from sale of assets		$ 56,400
Gain (loss) on sale of assets		$ 500