Offsetting Assets And Liabilities (Offsetting of Financial Assets and Derivative Assets) (Details) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Futures Contracts [Member]
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	$ 33,713,180	$ 0
Gross Amounts Offset in the Statements of Financial Condition	0	0
Net Amounts of Assets Presented in the Statements of Financial Condition	33,713,180	0
Swap [Member]
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	5,410,413	0
Gross Amounts Offset in the Statements of Financial Condition	0	0
Net Amounts of Assets Presented in the Statements of Financial Condition	$ 5,410,413	$ 0