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Derivative Instruments - Additional Information (Detail) (USD $)
In Thousands, unless otherwise specified
6 Months Ended
Jun. 30, 2014
Dec. 31, 2013
Jun. 30, 2014
7.25% Senior Unsecured Notes due 2019
Jun. 30, 2014
Commodity contracts
Entity
Jun. 30, 2014
Commodity contracts
Credit Concentration Risk
Entity
Jun. 30, 2014
Commodity contracts
Natural Gas
Jun. 30, 2014
Commodity contracts
Crude Oil
Derivative Instruments and Hedging Activities Disclosure [Line Items]              
Third-party quoted forward prices           NYMEX Henry Hub gas West Texas Intermediate crude oil
Annual interest rate     7.25%        
Derivative assets $ 0 $ 5,382          
Number of derivative counterparty       7 5