Dispositions - Additional Information (Detail)	3 Months Ended									12 Months Ended
	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($) a	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
(Loss) gain on the sale of assets	$ 407,000	$ (36,341,000)	$ 5,867,000	$ (189,000)	$ (10,815,000)	$ (30,000)	$ 156,000	$ 23,000		$ (30,256,000)	$ (10,666,000)	$ 23,716,000
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										337,000	(448,000)	870,000
Proceeds from sale of oil and gas properties										$ 938,000	$ 1,200,000	1,300,000
Northern Oklahoma
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
(Loss) gain on the sale of assets						(39,000)
Proceeds from sale of oil and gas properties						$ 23,300,000
Texas Panhandle Properties
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
(Loss) gain on the sale of assets									$ (989,000)
Proceeds from sale of oil and gas properties									$ 40,400,000
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												23,800,000
Proceeds from sale of oil and gas properties												$ 30,800,000
Pennsylvania
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
(Loss) gain on the sale of assets		$ (36,500,000)	5,900,000		$ (10,200,000)
Percentage of royalty disposed		2.50%			1.00%						1.00%
Proceeds from sale of oil and gas properties		$ 750,000,000.0	$ 34,000,000.0		$ 300,000,000.0
Pennsylvania | Natural Gas and Oil Properties
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of acres sold | a			20,000