Fair Value Measurements - Additional Information (Detail) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) Company Lenders	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Interest and dividends	$ 164	$ 151	$ 412	$ 322
Mark-to-market gain (loss)	(4,500)	(1,200)	(3,700)	1,300
Impairment of proved properties and other assets	502,233	$ 0	502,233	24,991
Allowance for doubtful accounts on accounts receivable	3,306		$ 3,306		$ 2,719
Number of financial institutions included in counter parties | Company			17
Number of secured lenders not in banking credit facility | Lenders			2
Net derivative assets	18,400		$ 18,400
Fair Value, Measurements, Nonrecurring | Natural Gas and Oil Properties
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impairment of proved properties and other assets	$ 502,233		$ 502,233	$ 24,991