Summary of Significant Accounting Policies - Summary of Average Monthly Notional Value of Future Contracts Outstanding (Detail) - USD ($)	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Weighted Average [Member] \| Commodity Currency Contract [Member]
Derivative [Line Items]
Average Notional Value - Short	$ 41,955,992	$ 43,481,259	$ 55,079,954

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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