Investments in Affiliates - Additional Information (Detail) - USD ($)		3 Months Ended
		Mar. 31, 2020	Dec. 31, 2019
Investments In And Advances To Affiliates [Line Items]
United States Treasury Obligations, at value		$ 76,994,177	$ 55,798,273
Treasury obligation measurement maximum maturity period		12 months
United States Treasury Obligations [Member]
Investments In And Advances To Affiliates [Line Items]
United States Treasury Obligations, at value	[1]	$ 76,994,177	$ 55,798,273
United States Treasury Obligations [Member] | Affiliated Investments [Member]
Investments In And Advances To Affiliates [Line Items]
Treasury obligation measurement minimum maturity period		1 month
Treasury obligation measurement maximum maturity period		12 months
United States Treasury Obligations [Member] | Affiliated Investments [Member] | Minimum [Member]
Investments In And Advances To Affiliates [Line Items]
United States Treasury Obligations, at value		$ 300,000,000

[1] Security may be traded on a discount basis. The interest rate shown represents the discount rate at the most recent auction date of the security prior to period end.