Fair Value Measurements - Additional Information (Detail)	3 Months Ended		6 Months Ended	9 Months Ended
	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2016 Counterparty	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Interest and dividends	$ 192,000	$ 164,000		$ 509,000	$ 412,000
Mark-to-market gain (loss)	2,300,000	(4,500,000)		3,700,000	(3,700,000)
Impairment on natural gas and oil properties	0	502,233,000		43,040,000	502,233,000
Allowance for doubtful accounts on accounts receivable	5,555,000			5,555,000		$ 4,994,000
Number of financial institutions included in counter parties | Counterparty			24
Number of counterparties | Counterparty			6
Net derivative asset	$ 24,100,000			24,100,000
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
Northern Oklahoma and Northwest Pennsylvania
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impairment on natural gas and oil properties		$ 502,200,000			$ 502,200,000