Trading Activities - Gross Fair Values of Derivative Instruments of Futures and Forward Contracts as Separate Assets and Liabilities (Detail) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Futures Contracts [Member]
Derivative [Line Items]
Total unrealized appreciation on open contracts	$ 1,455,308	$ 1,456,716
Total unrealized depreciation on open contracts	(805,108)	(1,122,513)
Net unrealized appreciation (depreciation) on open contracts	650,200	334,203
Futures Contracts [Member] | Commodity [Member]
Derivative [Line Items]
Total unrealized appreciation on open contracts	563,455	508,863
Total unrealized depreciation on open contracts	(223,403)	(389,356)
Futures Contracts [Member] | Equity [Member]
Derivative [Line Items]
Total unrealized appreciation on open contracts	498,738	248,473
Total unrealized depreciation on open contracts	(133,469)	(229,595)
Futures Contracts [Member] | Currencies [Member]
Derivative [Line Items]
Total unrealized appreciation on open contracts	195,187	241,791
Total unrealized depreciation on open contracts	(59,373)	(78,105)
Futures Contracts [Member] | Interest Rates [Member]
Derivative [Line Items]
Total unrealized appreciation on open contracts	197,928	457,589
Total unrealized depreciation on open contracts	(388,863)	(425,457)
Forward Contracts [Member]
Derivative [Line Items]
Total unrealized appreciation on open contracts	227,718	623,038
Total unrealized depreciation on open contracts	(489,107)	(632,108)
Net unrealized appreciation (depreciation) on open contracts	(261,389)	(9,070)
Forward Contracts [Member] | Commodity [Member]
Derivative [Line Items]
Total unrealized appreciation on open contracts	123,549	374,564
Total unrealized depreciation on open contracts	(235,526)	(230,751)
Forward Contracts [Member] | Currencies [Member]
Derivative [Line Items]
Total unrealized appreciation on open contracts	104,169	248,474
Total unrealized depreciation on open contracts	$ (253,581)	$ (401,357)