Investments (Details) - Interest Rate Risk [Member] - USD ($)		Sep. 30, 2017	Jun. 30, 2017
Risks Inherent in Servicing Assets and Servicing Liabilities [Line Items]
Receivable on open futures contracts	[1]	$ 240,407	$ 21,795
Written options, at fair value	[2]	$ (8,500)	$ (3,477)

[1] Represents cumulative appreciation of futures contracts as reported in the Statements of Assets and Liabilities.

[2] Represents fair value of options contracts as reported in the Statements of Assets and Liabilities.