Service Providers and Related Party Agreements - Additional Information (Detail)	6 Months Ended
Jun. 30, 2019
Related Party Transactions [Abstract]
Annual nominal rate at which the Sponsor's fee accrues	0.40%

Identify the stated interest rate per the agreement, for example, leasing and debt arrangements between related parties.

No definition available.

Name:	us-gaap_RelatedPartyTransactionRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration