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Fair Value of Financial Instruments (Effect of Derivative Instruments on Condensed Statements of Operations) (Details) (USD $)
3 Months Ended
Mar. 31, 2014
Mar. 31, 2013
Derivative Instruments, Gain (Loss) [Line Items]    
Realized Gain or (Loss) on Derivatives Recognized in Income $ 525,150 $ 1,165,190
Change in Unrealized Gain or (Loss) on Derivatives Recognized in Income 1,106,210 2,312,560
Commodity Contracts | Futures | Realized gain on closed positions
   
Derivative Instruments, Gain (Loss) [Line Items]    
Realized Gain or (Loss) on Derivatives Recognized in Income 525,150 1,165,190
Commodity Contracts | Futures | Change in unrealized gain (loss) on open positions
   
Derivative Instruments, Gain (Loss) [Line Items]    
Change in Unrealized Gain or (Loss) on Derivatives Recognized in Income $ 1,106,210 $ 2,312,560