Investments in Affiliates - Summary of Transactions in, and Earnings from, Investments in Affiliates (Excluding Affiliated Money Market Funds) (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2021		Mar. 31, 2020
Investments In And Advances To Affiliates [Line Items]
Beginning Value	$ 891,104,755
Change in Unrealized Appreciation (Depreciation)	99,032		$ 134,500
Ending Value	978,309,593
Affiliated Investments [Member]
Investments In And Advances To Affiliates [Line Items]
Beginning Value	891,104,755		767,882,587
Purchases at Cost	966,097,731		317,285,890
Proceeds from Sales	(878,918,579)		(801,752,087)
Change in Unrealized Appreciation (Depreciation)	25,686		1,542,060
Ending Value	978,309,593		284,958,450
Dividend Income	89,577		2,028,849
Affiliated Investments [Member] | Invesco Government & Agency Portfolio, Institutional Class [Member]
Investments In And Advances To Affiliates [Line Items]
Beginning Value	710,155,447
Purchases at Cost	966,097,731
Proceeds from Sales	(878,918,579)
Ending Value	797,334,599
Dividend Income	62,658
Affiliated Investments [Member] | Money Market Mutual Fund - Invesco Premier U.S. Government Money Portfolio - Institutional Class [Member]
Investments In And Advances To Affiliates [Line Items]
Beginning Value			517,499,491
Purchases at Cost			317,285,890
Proceeds from Sales			(801,752,087)
Ending Value			33,033,294
Dividend Income			985,254
Affiliated Investments [Member] | Invesco Treasury Collateral ETF [Member]
Investments In And Advances To Affiliates [Line Items]
Beginning Value	180,949,308	[1]	250,383,096
Change in Unrealized Appreciation (Depreciation)	25,686		1,542,060
Ending Value	180,974,994	[1]	251,925,156
Dividend Income	$ 26,919		$ 1,043,595

[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.