XML 42 R27.htm IDEA: XBRL DOCUMENT v3.10.0.1
FINANCIAL HIGHLIGHTS (Per Unit Performance Data and Other Supplemental Financial Data) (Details) - $ / shares
 6 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Per Share Operating Performance:    
Net asset value, beginning of period [1] $ 23.34 $ 37.18
Total income (loss) 0.50 (9.85) [1]
Total expenses (0.13) (0.20) [1]
Net increase (decrease) in net asset value 0.37 (10.05) [1]
Net asset value, end of period $ 23.71 $ 27.13 [1]
Total Return 1.59% (27.02%)
Ratios to Average Net Assets    
Total income (loss) 8.31% (29.11%)
Management fees [2] 0.60% 0.60%
Expenses excluding management fees [2] 0.71% 0.73%
Net income (loss) 7.66% (29.77%)
[1] 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.
[2] Annualized.