Dispositions - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
(Loss) gain on the sale of assets	$ 23,000	$ 22,600,000
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	23,000	69,000
Proceeds from sale of oil and gas properties	$ 40,000	53,000
Western Oklahoma Property
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
(Loss) gain on the sale of assets		22,500,000
Proceeds from sale of oil and gas properties		$ 26,000,000