Derivative Instruments - Effect of Derivative Instruments on Statements of Income and Expenses (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Futures Contracts, Net Realized Gain (Loss)	$ (243,363)	$ (2,352,922)	$ (361,761)	$ (999,248)
Futures Contracts, Net Unrealized Gain (Loss)	470,684	(9,041)	(60,750)	(704,456)
Currency Futures Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Futures Contracts, Net Realized Gain (Loss)	(243,363)	(2,352,922)	(361,761)	(999,248)
Futures Contracts, Net Unrealized Gain (Loss)	470,684	(9,041)	(60,750)	(704,456)
Future Contracts, Net Realized and Unrealized Gain (Loss)	$ 227,321	$ (2,361,963)	$ (422,511)	$ (1,703,704)