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Derivative Instruments - Additional Information (Detail) (USD $)
In Thousands, unless otherwise specified
3 Months Ended
Mar. 31, 2014
Dec. 31, 2013
Mar. 31, 2014
7.25% Senior Unsecured Notes due 2019
Mar. 31, 2014
Commodity contracts
Entity
Mar. 31, 2014
Commodity contracts
Credit Concentration Risk
Entity
Mar. 31, 2014
Commodity contracts
Natural Gas
Mar. 31, 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 $ 2,039 $ 5,382   $ 2,000      
Number of derivative counterparty       5 3