Investments in Affiliates - Summary of Transactions in, and Earnings from, Investments in Affiliates (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Investments in and Advances to Affiliates [Line Items]
Beginning Value	$ 767,686,990
Change in Unrealized Appreciation (Depreciation)	(261,587)	$ (90,747)	$ 171,804
Ending Value	589,685,144	767,686,990
Dividend Income	23,910,823	21,577,336	24,359,948
Investment, Affiliated Issuer [Member]
Investments in and Advances to Affiliates [Line Items]
Beginning Value	521,903,775
Ending Value	589,685,144	521,903,775
Affiliated Investments [Member]
Investments in and Advances to Affiliates [Line Items]
Purchases at Cost	524,004,905	1,088,771,837	1,461,510,451
Proceeds from Sales	(456,280,226)	(934,677,851)	(1,611,536,659)
Change in Unrealized Appreciation (Depreciation)	56,690	(5,669)	279,064
Realized Gain (Loss)			0
Affiliated Investments [Member] | Investment, Affiliated Issuer [Member]
Investments in and Advances to Affiliates [Line Items]
Beginning Value	521,903,775	367,815,458	517,562,602
Ending Value	589,685,144	521,903,775	367,815,458
Dividend Income	23,910,823	21,577,336	24,359,948
Affiliated Investments [Member] | Invesco Government & Agency Portfolio, Institutional Class [Member]
Investments in and Advances to Affiliates [Line Items]
Purchases at Cost	524,004,905	1,088,771,837	1,431,035,264
Proceeds from Sales	(456,280,226)	(934,677,851)	(1,611,536,659)
Affiliated Investments [Member] | Invesco Government & Agency Portfolio, Institutional Class [Member] | Investment, Affiliated Issuer [Member]
Investments in and Advances to Affiliates [Line Items]
Beginning Value	402,174,495	248,080,509	428,581,904
Ending Value	469,899,174	402,174,495	248,080,509
Dividend Income	19,027,206	15,604,807	19,001,072
Affiliated Investments [Member] | Invesco Short Term Treasury ETF [Member]
Investments in and Advances to Affiliates [Line Items]
Purchases at Cost			30,475,187
Change in Unrealized Appreciation (Depreciation)	56,690	(5,669)	279,064
Affiliated Investments [Member] | Invesco Short Term Treasury ETF [Member] | Investment, Affiliated Issuer [Member]
Investments in and Advances to Affiliates [Line Items]
Beginning Value	119,729,280	119,734,949	88,980,698
Ending Value	119,785,970	119,729,280	119,734,949
Dividend Income	$ 4,883,617	$ 5,972,529	$ 5,358,876