Derivative Instruments - Summary of Gross and Net Amounts of Offsetting Assets and Liabilities (Detail) - Morgan Stanley & Co. LLC [Member] - Currency Futures Contracts [Member] - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Offsetting Assets And Liabilities [Line Items]
Financial Derivative Assets, Futures Contracts	$ 2,298,198	$ 5,197,738
Financial Derivative Liabilities, Futures Contracts	(1,779,724)	(7,972,637)
Net value of derivatives, Assets	518,474
Net amount	$ 518,474
Net value of derivatives, Liabilities		(2,774,899)
Collateral (Received)/Pledged, Non-Cash		$ 2,774,899