Fair Value Measurements - Additional Information (Detail)	1 Months Ended	3 Months Ended		6 Months Ended
	Aug. 31, 2020 USD ($)	Mar. 31, 2021 USD ($) Counterparty	Mar. 31, 2020 USD ($)	Dec. 31, 2020 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Interest and dividends		$ 109,000	$ 148,000
Mark-to-market gain (loss)		2,000,000.0	$ (10,500,000)
Impairment of proved properties and other assets		0
Allowance for doubtful accounts on accounts receivable		$ 3,004,000		$ 3,004,000
Number of derivative counterparties | Counterparty		20
Number of counter parties that are not participants in bank credit facility | Counterparty		1
Counterparties not in Facility
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net derivative asset		$ (2,300,000)
One Counterparty Not in Facility
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net derivative asset		5,700,000
North Louisiana | Fair Value, Inputs, Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impairment of proved properties and other assets		77,000,000.0
Maximum | North Louisiana | Contingent Consideration
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Potential contractual payout of contingent consideration	$ 90,000,000.0	$ 75,000,000.0		$ 0
Measurement Input, Price Volatility | Weighted Average
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Implied volatilities		65.00%
Measurement Input, Price Volatility | Weighted Average | Swaptions | Crude Oil1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Implied volatilities		29.00%
Measurement Input, Price Volatility | Weighted Average | Swaptions | Natural Gas
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Implied volatilities		22.00%
Measurement Input, Price Volatility | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Implied volatilities		50.00%
Measurement Input, Price Volatility | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Implied volatilities		86.00%