Trading Activities - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018 USD ($) Contract	Dec. 31, 2017 USD ($) Contract
Futures Contracts [Member]
Derivative [Line Items]
Average number of derivative contracts traded	3,115	4,357
Forward Contracts [Member] | Commodity [Member] | Metals [Member]
Derivative [Line Items]
Average number of derivative contracts traded	347	519
Forward Contracts [Member] | Currencies [Member]
Derivative [Line Items]
Average notional value of derivative | $	$ 96,190,765	$ 137,886,860
Off Exchange Traded [Member] | Minimum [Member]
Derivative [Line Items]
Percentage of total investments	16.90%
Off Exchange Traded [Member] | Maximum [Member]
Derivative [Line Items]
Percentage of total investments	39.70%