Service Providers and Related Party Agreements - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Related Party Transactions [Abstract]
Management fee percentage per annum of daily NAV			0.75%
Managing owner waived fees	$ 24,485	$ 8,522	$ 59,415	$ 8,522
Compensation for service to advisors			$ 0