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Derivative Instruments and Hedging Activities - Additional Information (Detail)
12 Months Ended
Dec. 31, 2015
USD ($)
counterparty
Dec. 31, 2014
USD ($)
Dec. 31, 2013
USD ($)
Dec. 31, 2012
USD ($)
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 $ 17,952,000 $ 83,315,000 $ (2,062,000) $ 28,833,000
Accumulated other comprehensive income, to be reclassified into earnings in the next twelve months 24,025,000      
Potential impact of the rights of offset 0      
Cash Flow Hedges [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Accumulated other comprehensive income $ 24,025,000 $ 86,783,000 $ (1,395,000) $ 28,833,000
Fixed-Price Swaps And Costless Collars [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Number of counterparties | counterparty 2      
Two Counterparties [Member] | Fixed-Price Swaps And Costless Collars [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Counterparty contract volume percentage 86.00%