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Fair Value of Financial Instruments (Valuation of Securities Using Fair Value Hierarchy) (Details) (USD $)
Dec. 31, 2013
Dec. 31, 2012
Short-Term Investments
   
Schedule of Trading Securities and Other Trading Assets [Line Items]    
Securities, fair value $ 59,154,742 $ 92,755,785
Exchange-Traded Futures Contracts | United States
   
Schedule of Trading Securities and Other Trading Assets [Line Items]    
Securities, fair value 1,642,450 1,556,910
Fair Value, Inputs, Level 1 | Short-Term Investments
   
Schedule of Trading Securities and Other Trading Assets [Line Items]    
Securities, fair value 59,154,742 92,755,785
Fair Value, Inputs, Level 1 | Exchange-Traded Futures Contracts | United States
   
Schedule of Trading Securities and Other Trading Assets [Line Items]    
Securities, fair value $ 1,642,450 $ 1,556,910