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 held	1,762	1,874
Options Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Average number of derivative contracts held	181	75
Forward Contracts [Member] | Currencies [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Average notional value of derivative | $	$ 3,510,381	$ 63,983,108