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FINANCIAL HIGHLIGHTS (Per share Performance Data and Other Supplemental Financial Data) (Detail) - $ / shares | 3 Months Ended
--- | ---
Mar. 31, 2016 | Mar. 31, 2015
Per Share Operating Performance: |  |  |
Net asset value, beginning of year |  | $ 11.02 | $ 20.15
Total income (loss) |  | (1.26) | (3.25)
Total expenses |  | (0.02) | (0.03)
Net increase (decrease) in net asset value |  | (1.28) | (3.28)
Net asset value, end of year |  | $ 9.74 | $ 16.87
Total Return |  | (11.62%) | (16.28%)
Ratios to Average Net Assets |  |  |
Total income (loss) |  | (4.91%) | (11.82%)
Management fees | [1] | 0.45% | 0.45%
Expenses excluding management fees | [1] | 0.37% | 0.27%
Net income (loss) |  | (5.11%) | (12.00%)
[1] | Annualized.

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