Derivative Instruments and Hedging Activities - Additional Information (Detail) $ in Thousands		6 Months Ended
	Aug. 02, 2016 counterparty	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Maximum correlation between price of oil & natural gas in market and underlying price basis indicative in the derivative contract		100.00%
Accumulated other comprehensive income (loss)		$ 7,385	$ 18,700	$ 17,952	$ 40,700	$ 70,800	$ 83,300
Accumulated other comprehensive income, to be reclassified into earnings in the next twelve months		7,400
Fair value of derivative contracts		37		0
Cash Flow Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Accumulated other comprehensive income (loss)		$ 7,400	$ 18,700	$ 24,000	$ 46,500	$ 77,900	$ 86,800
Subsequent Event
Derivative Instruments, Gain (Loss) [Line Items]
Percentage of counterparty contract volume	86.00%
Subsequent Event | Fixed-Price Swaps And Costless Collars
Derivative Instruments, Gain (Loss) [Line Items]
Number of counterparties | counterparty	2