Trading Activities - Gross Fair Values of Derivative Instruments of Futures and Forward Contracts as Separate Assets and Liabilities (Detail) - USD ($)	Jun. 30, 2020	Dec. 31, 2019
Futures Contracts [Member]
Derivative [Line Items]
Total unrealized appreciation on open contracts	$ 761,303	$ 1,455,308
Total unrealized depreciation on open contracts	(256,232)	(805,108)
Net unrealized appreciation (depreciation) on open contracts	505,071	650,200
Futures Contracts [Member] | Commodity [Member]
Derivative [Line Items]
Total unrealized appreciation on open contracts	218,660	563,455
Total unrealized depreciation on open contracts	(85,614)	(223,403)
Futures Contracts [Member] | Equity [Member]
Derivative [Line Items]
Total unrealized appreciation on open contracts	140,120	498,738
Total unrealized depreciation on open contracts	(105,504)	(133,469)
Futures Contracts [Member] | Currencies [Member]
Derivative [Line Items]
Total unrealized appreciation on open contracts	11,007	195,187
Total unrealized depreciation on open contracts	(5,074)	(59,373)
Futures Contracts [Member] | Interest Rates [Member]
Derivative [Line Items]
Total unrealized appreciation on open contracts	391,516	197,928
Total unrealized depreciation on open contracts	(60,040)	(388,863)
Forward Contracts [Member]
Derivative [Line Items]
Total unrealized appreciation on open contracts	325,195	227,718
Total unrealized depreciation on open contracts	(388,988)	(489,107)
Net unrealized appreciation (depreciation) on open contracts	(63,793)	(261,389)
Forward Contracts [Member] | Commodity [Member]
Derivative [Line Items]
Total unrealized appreciation on open contracts	232,109	123,549
Total unrealized depreciation on open contracts	(275,556)	(235,526)
Forward Contracts [Member] | Currencies [Member]
Derivative [Line Items]
Total unrealized appreciation on open contracts	93,086	104,169
Total unrealized depreciation on open contracts	$ (113,432)	$ (253,581)