Fair Value Measurements - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2019 USD ($) Counterparty	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Interest and dividends	$ 179,000	$ 168,000
Mark-to-market gain (loss)	5,100,000	(7,500,000)
Allowance for doubtful accounts on accounts receivable	$ 6,118,000		$ 6,118,000
Number of derivative counterparties | Counterparty	20
Number of counter parties that are not participants in bank credit facility | Counterparty	4
Counterparties not in Facility
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net derivative liability	$ (3,900,000)
Natural Gas and Oil Properties | Fair Value, Measurements, Nonrecurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impairment on natural gas and oil properties	$ 0
Oklahoma
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impairment on natural gas and oil properties		7,300,000
Oklahoma | Natural Gas and Oil Properties | Fair Value, Measurements, Nonrecurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value		$ 32,500,000