Summary of Significant Accounting Policies - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2020 USD ($) Segment	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Accounts receivable	$ 60,621,000		$ 77,402,000
Depreciation, depletion, amortization and accretion	44,304,000	$ 29,950,000
Impairment of oil and gas properties	6,849,000
ARO liability current	$ 2,162,000
Number of operating segment | Segment	1
Amortization of deferred financing costs and debt discount	$ 1,000,000.0	1,000,000.0
Accrued Liabilities [Member]
Summary Of Significant Accounting Policies [Line Items]
ARO liability current	2,200,000		2,000,000.0
Oil and Gas Properties [Member]
Summary Of Significant Accounting Policies [Line Items]
Depreciation, depletion, amortization and accretion	43,700,000	29,500,000
Other property and equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Depreciation	$ 400,000	400,000
Other property and equipment [Member] | Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, expected lives	5 years
Other property and equipment [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, expected lives	40 years
Proved Oil And Gas Properties [Member] | Marcellus Shale [Member]
Summary Of Significant Accounting Policies [Line Items]
Impairment of oil and gas properties	$ 0	0
Unproved Oil And Gas Properties [Member]
Summary Of Significant Accounting Policies [Line Items]
Impairment of oil and gas properties	10,700,000	$ 9,600,000
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member]
Summary Of Significant Accounting Policies [Line Items]
Fair value of commodity derivative contracts	46,400,000		27,100,000
Revenue From Contract With Customer [Member]
Summary Of Significant Accounting Policies [Line Items]
Accounts receivable	$ 42,400,000		$ 63,700,000