XML 49 R27.htm IDEA: XBRL DOCUMENT v2.4.0.6
Per Unit Performance Data and Other Supplemental Financial Data (Detail) (USD $)
 9 Months Ended
Sep. 30, 2012
Sep. 30, 2011
Nov. 18, 2009
Per Unit Operating Performance:      
Net asset value, beginning of period $ 21.21 $ 35.02 $ 50.00
Total income (loss) $ (2.40) $ (6.85)  
Total expenses $ (0.13) $ (0.23)  
Net decrease in net asset value $ (2.53) $ (7.08)  
Net asset value, end of period $ 18.68 $ 27.94 $ 50.00
Total Return (11.93%) (20.22%)  
Ratios to Average Net Assets      
Total income (loss) (2.93%) (21.56%)  
Management fees* 0.75% [1] 0.75% [1]  
Total expenses excluding management fees* 0.39% [1] 0.65% [1]  
Expenses waived* (0.16%) [1] (0.44%) [1]  
Net expenses excluding management fees* 0.23% [1] 0.21% [1]  
Net income (loss) (3.66%) (22.28%)  
[1] Annualized.