Investments in Affiliates -Summary of Transactions in, and Earnings from, Investments in Affiliates (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Investments in and Advances to Affiliates [Line Items]
Investment Owned, at Fair Value, Beginning Balance			$ 426,822,433
Dividend Income	$ 1,873,948	$ 2,009,653	6,659,666	$ 7,219,100
Affiliated Investments [Member] | Money Market Mutual Fund - Invesco Government & Agency Portfolio, Institutional Class [Member]
Investments in and Advances to Affiliates [Line Items]
Investment Owned, at Fair Value, Beginning Balance	203,374,505	243,373,418	279,113,690	111,534,057
Purchases at Cost	66,394,889	196,908,586	639,916,156	686,047,529
Proceeds from Sales	(124,810,619)	(320,324,707)	(774,071,071)	(677,624,289)
Investment Owned, at Fair Value, Ending Balance	144,958,775	119,957,297	144,958,775	119,957,297
Dividend Income	$ 1,873,948	$ 2,009,653	$ 6,659,666	$ 7,219,100