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Derivative Contracts (Detail) (USD $)
12 Months Ended
Dec. 31, 2012
Derivative [Line Items]  
Fair Value (1,800,295)
Crude Oil Swap | Derivative Instrument 1
 
Derivative [Line Items]  
Monthly Volumes Bbls 1,933
Price per Bbl 76.74
Fair Value (1,077,333)
Crude Oil Swap | Derivative Instrument 2
 
Derivative [Line Items]  
Monthly Volumes Bbls 2,517
Price per Bbl 83.70
Fair Value (722,962)
Crude Oil Swap | Minimum | Derivative Instrument 1
 
Derivative [Line Items]  
Term 2013-01
Crude Oil Swap | Minimum | Derivative Instrument 2
 
Derivative [Line Items]  
Term 2011-07
Crude Oil Swap | Maximum | Derivative Instrument 1
 
Derivative [Line Items]  
Term 2014-12
Crude Oil Swap | Maximum | Derivative Instrument 2
 
Derivative [Line Items]  
Term 2015-12