XML 42 R27.htm IDEA: XBRL DOCUMENT v3.8.0.1
FINANCIAL HIGHLIGHTS (Per Unit Performance Data and Other Supplemental Financial Data) (Details) - $ / shares
 3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Per Share Operating Performance:    
Net asset value, beginning of period [1] $ 23.34 $ 37.18
Total income (loss) (0.73) (6.80) [1]
Total expenses (0.07) (0.10) [1]
Net increase (decrease) in net asset value (0.80) (6.90) [1]
Net asset value, end of period $ 22.54 $ 30.28 [1]
Total Return (3.43%) (18.51%)
Ratios to Average Net Assets    
Total income (loss) 2.85% (18.65%)
Management fees [2] 0.60% 0.60%
Expenses excluding management fees [2] 0.70% 0.73%
Net income (loss) 2.53% (18.97%)
[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.