Acquisitions and Divestitures - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended				3 Months Ended			4 Months Ended	8 Months Ended	12 Months Ended
	Oct. 31, 2015	Sep. 30, 2015	Aug. 31, 2015	May 31, 2015	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2016	Sep. 12, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Significant Acquisitions and Disposals
Loss (gain) on sales of assets, net								$ 49	$ (1,261)		$ (41,335)	$ (120,769)
Eagle Ford Shale, Lavaca County [Member]
Significant Acquisitions and Disposals
Proceeds from Sale of Oil and Gas Property and Equipment	$ 12,500
Gain on sale of oil and gas property										$ 9,500
Granite Wash [Member]
Significant Acquisitions and Disposals
Proceeds from Sale of Oil and Gas Property and Equipment	$ 100
East Texas [Member]
Significant Acquisitions and Disposals
Proceeds from Sale of Oil and Gas Property and Equipment			$ 73,000
Gain on sale of oil and gas property				$ 43,000
Disposal Group, Including Discontinued Operation, Property, Plant and Equipment				29,500
Disposal Group, Including Discontinued Operation, Assets				33,300
Disposal Group, Including Discontinued Operation, Asset Retirement Obligation				$ 3,800
Discontinued Operation, Income (Loss) from Discontinued Operation, before Income Tax										1,300	(27,500)
South Texas Oil Gathering Sys. Development Rights
Significant Acquisitions and Disposals
Proceeds from Sale of Intangible Assets					$ 147,100
Gain (Loss) on Disposition of Assets					147,100
Sale Leaseback Transaction, Recognized Gain, Net					63,000
Amount of the deferred gain recognized in the current period		$ 8,400							1,700	74,100
Sale Leaseback Transaction, Deferred Gain, Gross											84,100
Selma Chalk, MS Assets
Significant Acquisitions and Disposals
Proceeds from Sale of Oil and Gas Property and Equipment					$ 67,900
Impairment of property						$ 117,900						$ 117,900
South Texas Natural Gas Gathering Assets
Significant Acquisitions and Disposals
Sale Leaseback Transaction, Recognized Gain, Net							$ 56,700
Amount of the deferred gain recognized in the current period										400	400
Proceeds from Sale of Oil and Gas Property and Equipment							96,000
Loss (gain) on sales of assets, net							$ (67,300)		$ (300)	$ (9,500)
Non-core assets
Significant Acquisitions and Disposals
Proceeds from Sale of Oil and Gas Property and Equipment											2,900
Loss (gain) on sales of assets, net											$ (200)