FINANCIAL HIGHLIGHTS (Per Unit Performance Data and Other Supplemental Financial Data) (Details) (USD $)	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Nov. 18, 2009
Per Unit Operating Performance:
Net asset value, beginning of year	$ 21.21	$ 35.02	$ 53.77	$ 50.00
Total income (loss)	$ (3.78)	$ (13.42)	$ (18.21)
Net expenses	$ (0.20)	$ (0.39)	$ (0.54)
Net decrease in net asset value	$ (3.98)	$ (13.81)	$ (18.75)
Net asset value, end of year	$ 17.23	$ 21.21	$ 35.02	$ 50.00
Total Return	(18.76%)	(39.43%)	(34.87%)
Ratios to Average Net Assets
Total income (loss)	(11.80%)	(44.03%)	(37.65%)
Management fees	0.75%	0.75%	0.70%
Total expenses excluding management fees	0.40%	0.53%	0.66%
Expenses waived	(0.18%)	(0.36%)	(0.43%)
Net expenses excluding management fees	0.22%	0.17%	0.23%
Net income (loss)	(12.77%)	(44.95%)	(38.58%)