Financial Highlights (Details) (USD $)	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Per Unit operating performance: [Abstract]
Net asset value, period start (in dollars per unit)	$ 26.48		$ 27.76
Interest Income (in dollars per unit)	$ 0	[1]	$ 0
Expenses (in dollars per unit)	$ (0.50)		$ (0.56)
Realized/Unrealized Income (Loss) (in dollars per unit)	$ (1.59)	[2]	$ 1.18	[2]
Net Income (Loss) (in dollars per unit)	$ (2.09)	[3]	$ 0.62	[3]
Net asset value, period end (in dollars per unit)	$ 24.39		$ 28.38
Ratios to average net assets: [Abstract]
Net Investment Loss (in hundredths)	(8.20%)	[4]	(7.90%)	[4]
Expenses before Incentive Fees (in hundredths)	8.20%	[4]	8.00%	[4]
Expenses after Incentive Fees (in hundredths)	8.20%	[4]	8.00%	[4]
Total return before incentive fees (in hundredths)	(7.90%)		2.20%
Total return after incentive fees (in hundredths)	(7.90%)		2.20%

[1] Amounts less than $0.005 per Unit.

[2] Realized/Unrealized Income (Loss) is a balancing amount necessary to reconcile the change in net asset value per Unit with the other per Unit information.

[3] Based on change in net asset value per Unit.

[4] Annualized (except for incentive fees, if applicable).