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FINANCIAL HIGHLIGHTS (Per Unit Performance Data and Other Supplemental Financial Data) (Details) (USD $) | 3 Months Ended |
--- | --- | ---
Mar. 31, 2013 | Mar. 31, 2012 | Nov. 18, 2009
Per Unit Operating Performance: |  |  |  |  |
Net asset value, beginning of period | $ 17.23 |  | $ 21.21 |  | $ 50.00
Total income (loss) | $ 2.09 |  | $ (4.79) |  |
Total expenses | $ (0.04) |  | $ (0.05) |  |
Net increase (decrease) in net asset value | $ 2.05 |  | $ (4.84) |  |
Net asset value, end of period | $ 19.28 |  | $ 16.37 |  | $ 50.00
Total Return | 11.90% |  | (22.82%) |  |
Ratios to Average Net Assets |  |  |  |  |
Total income (loss) | 11.51% |  | (28.65%) |  |
Management fees | 0.75% |  | 0.75% |  |
Total expenses excluding management fees | 0.34% | [1] | 0.52% | [1] |
Expenses waived | (0.13%) | [1] | (0.28%) | [1] |
Net expenses excluding management fees | 0.21% | [1] | 0.24% | [1] |
Net income (loss) | 11.27% |  | (28.89%) |  |
[1] | Annualized

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