Investments in Affiliates - Summary of Transactions in, and Earnings from, Investments in Affiliates (Excluding Affiliated Money Market Funds) (Detail) - USD ($)	3 Months Ended			9 Months Ended
	Sep. 30, 2021		Sep. 30, 2020	Sep. 30, 2021		Sep. 30, 2020
Investments In And Advances To Affiliates [Line Items]
Beginning Value				$ 891,104,755
Change in Unrealized Appreciation (Depreciation)	$ 22,522		$ 11,894	(20,749)		$ (230,793)
Ending Value	1,399,157,279			1,399,157,279
Affiliated Investments [Member]
Investments In And Advances To Affiliates [Line Items]
Beginning Value	1,487,384,035		517,808,203	891,104,755		767,882,587
Purchases at Cost	845,704,716		827,404,464	2,905,207,909		1,806,051,012
Proceeds from Sales	(933,912,192)		(696,276,660)	(2,397,136,105)		(1,925,717,569)
Change in Unrealized Appreciation (Depreciation)	(19,280)		(119,868)	(19,280)		216,059
Realized Gain (Loss)						384,050
Ending Value	1,399,157,279		648,816,139	1,399,157,279		648,816,139
Dividend Income	79,176		160,952	250,169		2,762,551
Affiliated Investments [Member] | Invesco Government & Agency Portfolio, Institutional Class [Member]
Investments In And Advances To Affiliates [Line Items]
Beginning Value	1,306,434,727			710,155,447
Purchases at Cost	833,710,150		476,687,876	2,893,213,343		476,687,876
Proceeds from Sales	(933,912,192)		(8,923,789)	(2,397,136,105)		(8,923,789)
Ending Value	1,206,232,685		467,764,087	1,206,232,685		467,764,087
Dividend Income	79,175		1,486	220,869		1,486
Affiliated Investments [Member] | Money Market Mutual Fund [Member]
Investments In And Advances To Affiliates [Line Items]
Beginning Value			336,636,283			517,499,491
Purchases at Cost			350,716,588			1,329,363,136
Proceeds from Sales			(687,352,871)			(1,846,862,627)
Dividend Income			28,211			1,098,336
Affiliated Investments [Member] | Invesco Treasury Collateral ETF [Member]
Investments In And Advances To Affiliates [Line Items]
Beginning Value	180,949,308		181,171,920	180,949,308	[1]	250,383,096
Purchases at Cost	11,994,566			11,994,566
Proceeds from Sales						(69,931,153)
Change in Unrealized Appreciation (Depreciation)	(19,280)		(119,868)	(19,280)		216,059
Realized Gain (Loss)						384,050
Ending Value	192,924,594	[1]	181,052,052	192,924,594	[1]	181,052,052
Dividend Income	$ 1		$ 131,255	$ 29,300		$ 1,662,729

[1] Affiliated issuer. The issuer and/or the Fund is a wholly-owned subsidiary of Invesco Ltd., or is affiliated by having an investment adviser that is under common control of Invesco Ltd. See Note 8.