Organization - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2021 CreationUnit shares	Dec. 31, 2020 shares
Organization Consolidation And Presentation Of Financial Statements [Abstract]
General shares, shares issued	40	40
Treasury obligation measurement maximum maturity period	12 months
Minimum number of Creation Units that can be purchased | CreationUnit	1
Number of shares issued per Creation Unit	100,000