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	$ 305,732	$ (1,170,818)	$ 222,117
Currencies [Member]
Derivative [Line Items]
Total trading results	(522,483)	205,969	219,420
Energy [Member]
Derivative [Line Items]
Total trading results	(118,612)	(471,773)	1,020,372
Grains [Member]
Derivative [Line Items]
Total trading results	(194,106)	(803,721)	(81,019)
Indices [Member]
Derivative [Line Items]
Total trading results	517,449	497,548	(152,017)
Interest Rates U.S. [Member]
Derivative [Line Items]
Total trading results	220,851	(254,500)	(1,253,337)
Interest Rates Non-U.S. [Member]
Derivative [Line Items]
Total trading results	322,348	29,826	1,238,890
Livestock [Member]
Derivative [Line Items]
Total trading results	(105,180)	(29,930)	(54,052)
Metals [Member]
Derivative [Line Items]
Total trading results	170,796	(1,540)	(454,501)
Softs [Member]
Derivative [Line Items]
Total trading results	$ 14,669	$ (342,697)	$ (261,639)