Derivative Instruments - Summary of Average Monthly Notional Value of Future Contracts Outstanding (Detail) - USD ($)	3 Months Ended	9 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Weighted Average [Member] \| Currency Futures Contracts [Member]
Derivative [Line Items]
Average Notional Value	$ 575,781,464	$ 792,901,625	$ 678,781,882	$ 857,795,958

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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