Property, Plant and Equipment - Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Impairment loss		$ 384,000	$ 0	$ 0
Impairment charge		10,257,000	384,228,000	6,887,000
Held-for-sale
Property, Plant and Equipment [Line Items]
Impairment loss		4,400,000
Held-for-sale | Foreman Butte Divestiture
Property, Plant and Equipment [Line Items]
Impairment loss	$ 383,400,000		383,400,000
Proved oil and gas properties
Property, Plant and Equipment [Line Items]
Asset retirement costs		42,300,000	40,500,000
Impairment charge		0		0
Other property and equipment
Property, Plant and Equipment [Line Items]
Asset retirement costs		1,400,000	1,300,000
Unproved oil and gas properties
Property, Plant and Equipment [Line Items]
Impairment charge		$ 5,400,000	$ 900,000	$ 6,900,000