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Offsetting Assets And Liabilities (Offsetting of Financial Assets and Derivative Assets) (Details) (Futures Contracts [Member], USD $)
Mar. 31, 2013
Dec. 31, 2012
Futures Contracts [Member]
   
Offsetting Assets [Line Items]    
Gross Amounts of Recognized Assets $ 4,023,690 $ 374,190
Gross Amounts Offset in the Statements of Financial Condition 0 0
Net Amounts of Assets Presented in the Statements of Financial Condition $ 4,023,690 $ 374,190