Investments in Affiliates - Additional Information (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Investments In And Advances To Affiliates [Line Items]
Treasury obligation measurement maximum maturity period	12 months
United States Treasury Obligations, at value	$ 119,981,596	$ 123,646,647
United States Treasury Obligations [Member]
Investments In And Advances To Affiliates [Line Items]
United States Treasury Obligations, at value	$ 119,981,596	$ 123,646,647
Affiliated Investments [Member] | United States Treasury Obligations [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
Affiliated Investments [Member] | United States Treasury Obligations [Member] | Minimum [Member]
Investments In And Advances To Affiliates [Line Items]
United States Treasury Obligations, at value	$ 300,000,000