Trading Activities - Trading Gains and Losses by Market Sector on Derivative Instruments Traded (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Total trading results	$ (13,778,323)	$ 3,887,298	$ (22,801,614)
Currencies [Member]
Derivative [Line Items]
Total trading results	(3,364,175)	(7,867,522)	3,080,007
Energy [Member]
Derivative [Line Items]
Total trading results	2,715,862	(106,263)	(12,279,027)
Grains [Member]
Derivative [Line Items]
Total trading results	(3,115,089)	(4,270,109)	(210,422)
Indices [Member]
Derivative [Line Items]
Total trading results	(6,559,366)	29,363,266	(6,694,075)
Interest Rates U.S. [Member]
Derivative [Line Items]
Total trading results	(2,158,832)	(4,548,710)	(4,607,629)
Interest Rates Non-U.S. [Member]
Derivative [Line Items]
Total trading results	(631,329)	(7,142,822)	4,717,308
Livestock [Member]
Derivative [Line Items]
Total trading results	(155,263)	(902,168)	(1,279,792)
Metals [Member]
Derivative [Line Items]
Total trading results	(1,219,114)	(404,789)	(4,359,666)
Softs [Member]
Derivative [Line Items]
Total trading results	$ 708,983	$ (233,585)	$ (1,168,318)