Trading Activities - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018 USD ($) Contracts	Dec. 31, 2017 USD ($) Contracts
Futures Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Average number of derivative contracts traded	7,474	20,043
Forward Contracts [Member] | Metals [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Average number of derivative contracts traded	758	2,202
Forward Contracts [Member] | Currencies [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Average number of derivative contracts traded | $	$ 316,081,746	$ 1,253,145,597