Trading Activities - Summary of Gross Fair Values of Derivative Instruments of Futures and Forward Contracts as Separate Assets and Liabilities (Detail) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Futures Contracts [Member]
Derivative [Line Items]
Total unrealized appreciation on open contracts	$ 3,370,017	$ 6,470,501
Total unrealized depreciation on open contracts	(4,422,974)	(1,945,563)
Net unrealized appreciation (depreciation) on open contracts	(1,052,957)	4,524,938
Futures Contracts [Member] | Commodity [Member]
Derivative [Line Items]
Total unrealized appreciation on open contracts	1,479,301	3,582,239
Total unrealized depreciation on open contracts	(1,605,268)	(538,303)
Futures Contracts [Member] | Equity [Member]
Derivative [Line Items]
Total unrealized appreciation on open contracts	603,645	1,462,121
Total unrealized depreciation on open contracts	(1,004,340)	(436,625)
Futures Contracts [Member] | Currencies [Member]
Derivative [Line Items]
Total unrealized appreciation on open contracts	12,269	76,914
Total unrealized depreciation on open contracts	(61,986)	(11,984)
Futures Contracts [Member] | Interest Rates [Member]
Derivative [Line Items]
Total unrealized appreciation on open contracts	1,274,802	1,349,227
Total unrealized depreciation on open contracts	(1,751,380)	(958,651)
Forward Contracts [Member]
Derivative [Line Items]
Total unrealized appreciation on open contracts	1,880,468	3,276,785
Total unrealized depreciation on open contracts	(2,164,284)	(1,985,045)
Net unrealized appreciation (depreciation) on open contracts	(283,816)	1,291,740
Forward Contracts [Member] | Commodity [Member]
Derivative [Line Items]
Total unrealized appreciation on open contracts	751,884	1,760,347
Total unrealized depreciation on open contracts	(341,019)	(303,656)
Forward Contracts [Member] | Currencies [Member]
Derivative [Line Items]
Total unrealized appreciation on open contracts	1,128,584	1,516,438
Total unrealized depreciation on open contracts	$ (1,823,265)	$ (1,681,389)