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FINANCIAL HIGHLIGHTS (Tables) | 9 Months Ended
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Sep. 30, 2018
Financial Highlights [Abstract] |
Per Unit Performance Data and Other Supplemental Financial Data | The following table presents per share performance data and other supplemental financial data for the nine months ended September 30, 2018 and 2017 for the shareholders. This information has been derived from information presented in the condensed financial statements.
|  | For the nine months ended September 30, 2018 (Unaudited) |  |  | For the nine months ended September 30, 2017 (Unaudited) |
Per Share Operating Performance: |  |  |  |  |  |  |  |
Net asset value, beginning of period |  | $ | 23.34 | * |  | $ | 37.18 | *
Total income (loss) |  |  | 1.73 |  |  |  | (10.73 | )*
Total expenses |  |  | (0.21 | ) |  |  | (0.27 | )*
Net increase (decrease) in net asset value |  |  | 1.52 |  |  |  | (11.00 | )*
Net asset value, end of period |  | $ | 24.86 |  |  | $ | 26.18 | *
Total Return |  |  | 6.51 | % |  |  | (29.60 | )%
Ratios to Average Net Assets |  |  |  |  |  |  |  |
Total income (loss) |  |  | 14.28 | % |  |  | (31.58 | )%
Management fees** |  |  | 0.60 | % |  |  | 0.60 | %
Expenses excluding management fees** |  |  | 0.70 | % |  |  | 0.68 | %
Net income (loss) |  |  | 13.31 | % |  |  | (32.54 | )%
| * | On January 4, 2018, there was a 1-for-4 reverse share split. Historical shares outstanding, net asset value per share and market value per share have been adjusted to reflect the 1-for-4 reverse share split on a retroactive basis.
| ** | Annualized.

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