Fair Value Measurements - Additional Information (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) Counterparty	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Interest and dividends	$ 181,000	$ 139,000	$ 317,000	$ 248,000
Mark-to-market gain (loss)	1,200,000	(576,000)	1,400,000	832,000
Impairment on natural gas and oil properties	0	$ 0	43,040,000	$ 0
Allowance for doubtful accounts on accounts receivable	4,722,000		$ 4,722,000		$ 4,994,000
Number of financial institutions included in counter parties | Counterparty			21
Number of counterparties | Counterparty			5
Net derivative asset	$ 1,900,000		$ 1,900,000
Western Oklahoma
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impairment on natural gas and oil properties			$ 43,040,000