Derivative Instruments - Effect of Derivative Instruments on Statements of Income and Expenses (Detail) - Currency Futures Contracts [Member] - Not Designated as Hedging Instrument [Member] - 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)	$ 2,428,298	$ 28,411,985	$ 1,494,520	$ 9,692,217
Futures Contracts, Net Unrealized Gain (Loss)	(4,973,433)	783,289	2,072,200	11,054,124
Future Contracts, Net Realized and Unrealized Gain (Loss)	$ (2,545,135)	$ 29,195,274	$ 3,566,720	$ 20,746,341