Service Providers and Related Party Agreements - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Related Party Transactions [Abstract]
Management fee percentage per annum of daily NAV			0.75%
Fee waiver term			The Managing Owner has contractually agreed to waive indefinitely the fees that it receives in an amount equal to the indirect management fees that the Fund incurs through its investments in affiliated money market mutual funds and/or affiliated T-Bill ETFs. The Managing Owner may terminate this fee waiver on 60 days notice.
Managing owner waived fees	$ 9,446	$ 10,699	$ 31,854	$ 31,563