Oil and Natural Gas Properties - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Oil and Gas Exploration and Production Industries Disclosures [Abstract]
Depletion expense on capitalized oil and natural gas properties	$ 36,700,000	$ 10,700,000	$ 82,400,000	$ 22,000,000
Amortization expense	11,200,000	0	25,600,000	0
Abandonment and impairment expense		$ 4,200,000		$ 4,500,000
Impaired expense	$ 0		$ 0