Service Providers and Related Party Agreements - Additional Information (Detail) - USD ($)	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Related Party Transactions [Abstract]
Management fee percentage per annum of daily NAV	0.75%
Managing owner waived fees	$ 25,808	$ 19,344
Compensation for service from advisors	$ 0

Amount of fees earned from providing investment advice and research to customers.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.13(a),(d))
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

Name:	us-gaap_InvestmentAdvisoryFees
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration