Financial Highlights (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Class 0 Units [Member]
Per unit operating performance [Abstract]
Net asset value per unit, beginning balance (in dollars per units)	$ 127.72	$ 114.88
Net income [Abstract]
Net investment loss (in dollars per unit)	$ (3.39)	$ (3.32)
Net gain on investments	$ 25.04	$ 16.16
Net income (in dollars per unit)	$ 21.65	$ 12.84
Net asset value per unit, ending balance (in dollars per unit)	$ 149.37	$ 127.72
Ratios to average members' capital and total return [Abstract]
Total return before Incentive Allocation (in hundredths)	19.75%	11.18%
Incentive Allocation (in hundredths)	(2.80%)	0.00%
Total return after Incentive Allocation (in hundredths)	16.95%	11.18%
Net investment loss before Incentive Allocation (in hundredths)	(2.73%)	(2.74%)
Incentive Allocation (in hundredths)	(2.75%)	0.00%
Net investment loss after Incentive Allocation (in hundredths)	(5.48%)	(2.74%)
Total expenses before Incentive Allocation (in hundredths)	2.93%	2.95%
Incentive Allocation (in hundredths)	2.75%	0.00%
Total expenses after Incentive Allocation (in hundredths)	5.68%	2.95%
Class 2 Units [Member]
Per unit operating performance [Abstract]
Net asset value per unit, beginning balance (in dollars per units)	$ 98.41	$ 90.29
Net income [Abstract]
Net investment loss (in dollars per unit)	$ (4.53)	$ (4.47)
Net gain on investments	$ 19.70	$ 12.59
Net income (in dollars per unit)	$ 15.17	$ 8.12
Net asset value per unit, ending balance (in dollars per unit)	$ 113.58	$ 98.41
Ratios to average members' capital and total return [Abstract]
Total return before Incentive Allocation (in hundredths)	17.38%	8.99%
Incentive Allocation (in hundredths)	(1.96%)	0.00%
Total return after Incentive Allocation (in hundredths)	15.42%	8.99%
Net investment loss before Incentive Allocation (in hundredths)	(4.78%)	(4.75%)
Incentive Allocation (in hundredths)	(1.92%)	0.00%
Net investment loss after Incentive Allocation (in hundredths)	(6.70%)	(4.75%)
Total expenses before Incentive Allocation (in hundredths)	4.98%	4.95%
Incentive Allocation (in hundredths)	1.92%	0.00%
Total expenses after Incentive Allocation (in hundredths)	6.90%	4.95%