Property Dispositions - Additional Information (Detail) $ in Thousands	1 Months Ended		3 Months Ended					12 Months Ended
	Oct. 31, 2017 USD ($)	Sep. 30, 2017 USD ($) a	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($) a Boe	Dec. 31, 2016 USD ($)	Sep. 30, 2016 a Boe	Jun. 30, 2016 USD ($) a	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($) Boe	Dec. 31, 2015 USD ($)	Oct. 14, 2016 a
Property Acquisition And Dispositions [Line Items]
Proceeds from sale of assets					$ 214,800			$ 144,353	$ 631,549	$ 34,008
Proceeds from sale of non-producing leasehold					295,600		$ 110,000			25,900
Gain (Loss) on disposition of non-producing leasehold					$ 201,000		$ 96,900			$ 20,500
Arkoma Woodford [Member]
Property Acquisition And Dispositions [Line Items]
Proceeds from Sale of Oil and Gas Property and Equipment								65,300
Land Subject to Ground Leases | a		26,000		26,000
Production, Barrels of Oil Equivalents | Boe				1,700
Gain (Loss) on disposition of non-producing leasehold								(3,500)
STACK [Domain]
Property Acquisition And Dispositions [Line Items]
Proceeds from Sale of Oil and Gas Property and Equipment	$ 59,900	$ 3,600						63,500
Gain (Loss) on disposition of non-producing leasehold			$ 53,600	$ 3,300
OKLAHOMA
Property Acquisition And Dispositions [Line Items]
Proceeds from Sale of Oil and Gas Property and Equipment								7,200
Gain (Loss) on disposition of oil loading facilities								$ 4,200
SCOOP [Member]
Property Acquisition And Dispositions [Line Items]
Land Subject to Ground Leases | a											30,000
Production, Barrels of Oil Equivalents | Boe									700
WYOMING
Property Acquisition And Dispositions [Line Items]
Land Subject to Ground Leases | a							132,000
NORTH DAKOTA
Property Acquisition And Dispositions [Line Items]
Land Subject to Ground Leases | a						68,000
MONTANA
Property Acquisition And Dispositions [Line Items]
Land Subject to Ground Leases | a						12,000
BAKKEN [Domain]
Property Acquisition And Dispositions [Line Items]
Production, Barrels of Oil Equivalents | Boe						2,700