10. FINANCIAL HIGHLIGHTS - Financial highlights of the Partnership (Details)		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Class A [Member]
Total return for Limited Partners
Total return prior to incentive fees	[1]	(2.77%)	2.62%	(11.70%)	(6.91%)
Incentive fee	[1]	0.00%	0.00%	0.00%	0.00%
Total return after incentive fees	[1]	(2.77%)	2.62%	(11.70%)	(6.91%)
Ratio to average net asset value
Expenses prior to incentive fees	[2]	5.39%	4.75%	4.98%	4.65%
Incentive fees	[1]	0.00%	0.00%	0.00%	0.01%
Total expenses		5.39%	4.75%	4.98%	4.66%
Net investment loss	[2],[3]	(3.29%)	(2.80%)	(2.90%)	(3.05%)
Class B
Total return for Limited Partners
Total return prior to incentive fees	[1]	(2.30%)	2.14%	(10.38%)	(5.51%)
Incentive fee	[1]	(0.00%)	0.00%	(0.09%)	0.00%
Total return after incentive fees	[1]	(2.30%)	2.14%	(10.47%)	(5.51%)
Ratio to average net asset value
Expenses prior to incentive fees	[2]	3.47%	2.84%	3.22%	2.69%
Incentive fees	[1]	0.00%	0.00%	0.10%	0.00%
Total expenses		3.47%	2.84%	3.32%	2.69%
Net investment loss	[2],[3]	(1.37%)	0.93%	(1.14%)	(1.09%)
Institutional Interests [Member]
Total return for Limited Partners
Total return prior to incentive fees	[1]	(2.09%)	1.93%	(9.81%)	(4.91%)
Incentive fee	[1]	0.00%	0.01%	0.00%	(0.01%)
Total return after incentive fees	[1]	(2.09%)	1.94%	(9.81%)	(4.92%)
Ratio to average net asset value
Expenses prior to incentive fees	[2]	2.64%	1.87%	2.25%	1.80%
Incentive fees	[1]	0.00%	0.01%	0.00%	0.01%
Total expenses		2.64%	1.88%	2.25%	1.81%
Net investment loss	[2],[3]	(0.53%)	(0.10%)	(0.16%)	(0.27%)

[1] Not annualized.

[2] Annualized.

[3] Excludes incentive fee.