Trading Activities - Additional Information (Detail) - Weighted Average [Member]	3 Months Ended
	Mar. 31, 2018 USD ($) Contract	Mar. 31, 2017 USD ($) Contract
Futures Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Average number of derivative contracts traded	3,450	4,689
Forward Contracts [Member] | Commodity [Member] | Metals [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Average number of derivative contracts traded	425	607
Forward Contracts [Member] | Currencies [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Average notional value of derivative | $	$ 132,746,615	$ 123,410,631