Trading Activities - Trading Gains and Losses, by Market Sector, on Derivative Instruments (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivative [Line Items]
Total trading results	$ (899,778)	$ (1,522,800)	$ (1,827,426)	$ (2,192,622)
Commodity [Member]
Derivative [Line Items]
Total trading results	(225,973)	(548,754)	(838,355)	(2,866,174)
Equity [Member]
Derivative [Line Items]
Total trading results	(121,211)	1,892,065	(118,610)	5,835,287
Currencies [Member]
Derivative [Line Items]
Total trading results	(682,457)	(1,721,807)	(681,655)	(3,128,552)
Interest Rates [Member]
Derivative [Line Items]
Total trading results	$ 129,863	$ (1,144,304)	$ (188,806)	$ (2,033,183)