Derivative Instruments - Effect of Derivative Instruments on Statements of Income and Expenses (Detail) - Currency Futures Contracts [Member] - Not Designated as Hedging Instrument [Member] - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Futures contracts, realized gain (loss)	$ 5,422,705	$ 29,619,708	$ (51,958,105)
Futures contracts, unrealized gain (loss)	2,719,194	3,438,120	(9,961,447)
Future Contracts, Net Realized and Unrealized Gain (Loss)	$ 8,141,899	$ 33,057,828	$ (61,919,552)