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		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Futures Contracts, Net Realized Gain (Loss)	$ 6,743,928	$ 4,935,515	$ 8,238,448	$ 14,627,732
Futures Contracts, Net Unrealized Gain (Loss)	5,787,029	(1,231,473)	7,859,229	9,822,651
Future Contracts, Net Realized and Unrealized Gain (Loss)	$ 12,530,957	$ 3,704,042	$ 16,097,677	$ 24,450,383