Fair Value Measurements - Additional Information (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) Counterparty	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Interest and dividends	$ 1,500,000	$ 192,000	$ 2,400,000	$ 509,000
Mark-to-market gain (loss)	1,100,000	2,300,000	4,100,000	3,700,000
Impairment on natural gas and oil properties	63,679,000	$ 0	63,679,000	43,040,000
Allowance for doubtful accounts on accounts receivable	6,609,000		$ 6,609,000		$ 5,559,000
Number of financial institutions included in counter parties | Counterparty			22
Number of counterparties | Counterparty			5
Net derivative asset	20,800,000		$ 20,800,000
Oklahoma and Texas Panhandle
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impairment on natural gas and oil properties	$ 63,700,000		$ 63,700,000
Western Oklahoma
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impairment on natural gas and oil properties				$ 43,000,000