Statements Of Financial Condition (Parenthetical) (USD $)	Dec. 31, 2012	Dec. 31, 2011
United States Treasury Obligations, cost	$ 277,480,954	$ 437,494,687

This category includes investments in debt securities issued by the United States Department of the Treasury, US Government Agencies and US Government-sponsored Enterprises. Such securities may include treasury bills (short-term maturities - one year or less), treasury notes (intermediate term maturities - two to ten years), and treasury bonds (long-term maturities - ten to thirty years), debt securities issued by the Government National Mortgage Association (Ginnie Mae) and debt securities issued by the Federal National Mortgage Association (Fannie Mae) or the Federal Home Loan Mortgage Corporation (Freddie Mac).

No definition available.

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