Financial Highlights - Financial Highlights for Limited Partner Class (Detail) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Per Unit Performance (for a unit outstanding throughout the period):
Net realized and unrealized gains (losses)	$ (0.27)	$ 0.54	$ 0.73	$ 0.52
Net investment loss	(0.19)	(0.20)	(0.58)	(0.84)
Increase (decrease) for the period	(0.46)	0.34	0.15	(0.32)
Net asset value per Unit, beginning of period	14.81	13.88	14.20	14.54
Net asset value per Unit, end of period	$ 14.35	$ 14.22	$ 14.35	$ 14.22
Ratios to Average Limited Partners' Capital:
Net investment loss	(5.30%)	(5.50%)	(5.30%)	(7.20%)
Operating expenses before incentive fees	5.50%	5.50%	5.50%	5.60%
Incentive fees				1.60%
Operating expenses after incentive fees	5.50%	5.50%	5.50%	7.20%
Total return:
Total return before incentive fees	(3.10%)	2.40%	1.10%	(0.60%)
Incentive fees				(1.60%)
Total return after incentive fees	(3.10%)	2.40%	1.10%	(2.20%)