FINANCIAL HIGHLIGHTS (Details) - $ / shares |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Per Share Operating Performance: | |||
| Net asset value, beginning of year | $ 12.22 | $ 22.39 | $ 43.81 |
| Total income (loss) | 3.60 | (10.00) | (21.06) |
| Net expenses | (0.12) | (0.17) | (0.36) |
| Net increase (decrease) in Net Asset Value | 3.48 | (10.17) | (21.42) |
| Net asset value, end of year | $ 15.70 | $ 12.22 | $ 22.39 |
| Total Return | 28.48% | (45.42%) | (48.89%) |
| Ratios to Average Net Assets | |||
| Total income (loss) | 34.23% | (46.52%) | (68.25%) |
| Management fees | 0.75% | 0.75% | 0.75% |
| Total expenses excluding management fees | 0.32% | 0.30% | 0.56% |
| Expenses waived | (0.17%) | (0.15%) | (0.39%) |
| Net expenses excluding management fees | 0.15% | 0.15% | 0.17% |
| Net income (loss) | 33.33% | (47.42%) | (69.17%) |