Fair Value Measurements - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended				12 Months Ended
	Aug. 31, 2020	Sep. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2018	Dec. 31, 2030	Dec. 31, 2026	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Aug. 14, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Interest and dividends								$ 713,000	$ 1,100,000	$ 1,100,000
Mark-to-market gain (loss)								$ 6,300,000	8,500,000	(7,900,000)
North Louisiana
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impairment of proved properties and other assets			$ 77,000,000.0	$ 1,100,000,000
Annual discount rate								12.00%
Divestiture contract obligation											$ 479,800,000
Estimated production volumes, percentage								34.00%
North Louisiana | Sensitivity Of Devemopment Plan
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Divestiture contract obligation								$ 29,000,000.0
North Louisiana | Sensitivity Flat Plant Allocation Percentage | Forecast
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Divestiture contract obligation						$ 17,900,000
Pennsylvania
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets, fair value										0
Oklahoma
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impairment of proved properties and other assets					$ 7,300,000					$ 15,300,000
North Louisiana Assets | Fair Value, Inputs, Level 2 | Leases
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impairment of proved properties and other assets								2,000,000.0
Houston | Fair Value, Inputs, Level 2 | Leases
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impairment of proved properties and other assets									$ 2,100,000
Minimum | North Louisiana | Forecast
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Estimated production volumes, percentage						34.00%
Maximum | North Louisiana | Forecast
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Estimated production volumes, percentage							100.00%
Maximum | North Louisiana | Contingent Consideration
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Potential Contractual Payout Of Contingent Consideration	$ 90,000,000	$ 90,000,000.0						$ 90,000,000.0
Measurement Input, Price Volatility | Weighted Average
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Implied volatilities								44.00%
Measurement Input, Price Volatility | Weighted Average | Swaption
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Implied volatilities								24.00%
Measurement Input, Price Volatility | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Implied volatilities								34.00%
Measurement Input, Price Volatility | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Implied volatilities								66.00%
Discount Rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Annual discount rate				12.00%					12.00%