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Changes in Asset Retirement Obligations (Detail) (USD $)
9 Months Ended
Sep. 30, 2013
Sep. 30, 2012
Reconciliation of Changes in Asset Retirement Obligations [Line Items]    
Asset retirement obligations, December 31, 2012 $ 1,336,151  
Liabilities incurred during the period 50,269  
Liabilities settled during the period (96,466)  
Liabilities of Black Raven acquired September 27, 2013 1,251,511  
Accretion 84,578 75,551
Asset retirement obligations, September 30, 2013 $ 2,626,043