Dispositions and Acquisitions - Dispositions - Additional Information (Detail) - USD ($)	1 Months Ended		3 Months Ended								6 Months Ended		9 Months Ended	12 Months Ended
	Feb. 28, 2015	Apr. 30, 2014	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Jun. 16, 2014	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 30, 2015	Dec. 31, 2014
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
(Loss) gain on the sale of assets			$ 470,000	$ (2,597,000)	$ (3,304,000)	$ (1,643,000)	$ (408,909,000)	$ (681,000)	$ 2,909,000	$ (175,000)				$ (7,074,000)	$ (406,856,000)		$ 285,638,000
Conger Exchange Transaction
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Cash proceeds from sale of assets		$ 145,000,000
Net operating income prior to disposition												$ 21,900,000
Gain on sale of assets after selling expenses																	272,700,000
Sale and exchange transaction, closing date														Jun. 16, 2014
Selling expenses for property sale																	$ 5,000,000
Net operating income prior to acquisition											$ 25,700,000
Recognized revenue from sale of property interests acquire											$ 33,800,000
Nora Gathering, LLC
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Percentage of ownership interest, acquired											50.00%						50.00%
Percentage ownership interest											50.00%						50.00%
Fair value of membership interest on acquisition date																	$ 134,800,000
Nora Gathering, LLC | Conger Exchange Transaction
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Gain on fair value of membership interest																	10,000,000
Western Oklahoma Properties
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
(Loss) gain on the sale of assets													$ (5,300,000)
Proceeds from sale of oil and gas properties													$ 78,600,000
Northeast Pennsylvania Non-operated Interest
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
(Loss) gain on the sale of assets						(2,100,000)
Proceeds from sale of oil and gas properties						$ 111,500,000
Miscellaneous Proved, Unproved Properties and Surface Acreage
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
(Loss) gain on the sale of assets														$ 302,000	943,000		3,000,000
Proceeds from sale of oil and gas properties														3,700,000	4,400,000		35,500,000
Mississippi and South Texas properties
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Proceeds from sale of oil and gas properties														$ 1,200,000
Virginia And West Virginia Property
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
(Loss) gain on the sale of assets							$ (407,700,000)								(407,700,000)
Cash proceeds from sale of assets															$ 876,000,000
Net operating income prior to disposition																$ 52,300,000	$ 98,300,000
West Texas Properties
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
(Loss) gain on the sale of assets	$ (101,000)
Proceeds from sale of oil and gas properties	$ 10,500,000