Financial Highlights - Financial Highlights for Limited Partner Class (Detail) - $ / shares		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Per Unit operating performance:
Net asset value at the beginning of the period		$ 11.80	$ 9.73	$ 12.72	$ 10.54
Net Investment Loss		(0.17)	(0.14)	(0.54)	(0.51)
Realized/Unrealized Gain (Loss)		0.53	1.52	(0.02)	1.08
Net Income (Loss)	[1]	0.36	1.38	(0.56)	0.57
Net asset value, September 30		$ 12.16	$ 11.11	$ 12.16	$ 11.11
Ratios to average net assets:
Net Investment Loss		(5.60%)	(5.40%)	(5.60%)	(6.90%)
Expenses before Incentive Fees		5.60%	5.40%	5.60%	6.90%
Incentive Fees		0.00%	0.00%	0.00%	0.00%
Expenses after Incentive Fees		5.60%	5.40%	5.60%	6.90%
Total return before Incentive Fees		3.10%	14.20%	(4.40%)	5.40%
Incentive Fees		0.00%	0.00%	0.00%	0.00%
Total return after Incentive Fees		3.10%	14.20%	(4.40%)	5.40%

[1] Represents the change in net asset value per Unit during the period.