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, 2020		Sep. 30, 2019	Sep. 30, 2020		Sep. 30, 2019
Investments In And Advances To Affiliates [Line Items]
Beginning Value				$ 767,882,587
Change in Unrealized Appreciation (Depreciation)	$ 11,894		$ (255,940)	(230,793)		$ 362,864
Ending Value	648,816,139			648,816,139
Affiliated Investments [Member]
Investments In And Advances To Affiliates [Line Items]
Beginning Value	517,808,203		349,869,627	767,882,587		395,084,923
Purchases at Cost	827,404,464		963,309,339	1,806,051,012		2,309,633,070
Proceeds from Sales	(696,276,660)		(996,517,834)	(1,925,717,569)		(2,388,424,582)
Change in Unrealized Appreciation (Depreciation)	(119,868)		(47,447)	216,059		320,274
Realized Gain (Loss)				384,050
Ending Value	648,816,139		316,613,685	648,816,139		316,613,685
Dividend Income	160,952		1,837,418	2,762,551		5,844,853
Affiliated Investments [Member] | Invesco Government & Agency Portfolio, Institutional Class [Member]
Investments In And Advances To Affiliates [Line Items]
Purchases at Cost	476,687,876			476,687,876
Proceeds from Sales	(8,923,789)			(8,923,789)
Ending Value	467,764,087			467,764,087
Dividend Income	1,486			1,486
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	336,636,283		99,356,050	517,499,491		144,939,067
Purchases at Cost	350,716,588		963,309,339	1,329,363,136		2,309,633,070
Proceeds from Sales	(687,352,871)		(996,517,834)	(1,846,862,627)		(2,388,424,582)
Ending Value			66,147,555			66,147,555
Dividend Income	28,211		453,882	1,098,336		1,514,967
Affiliated Investments [Member] | Invesco Treasury Collateral ETF [Member]
Investments In And Advances To Affiliates [Line Items]
Beginning Value	181,171,920		250,513,577	250,383,096	[1]	250,145,856
Proceeds from Sales				(69,931,153)
Change in Unrealized Appreciation (Depreciation)	(119,868)		(47,447)	216,059		320,274
Realized Gain (Loss)				384,050
Ending Value	181,052,052	[1]	250,466,130	181,052,052	[1]	250,466,130
Dividend Income	$ 131,255		$ 1,383,536	$ 1,662,729		$ 4,329,886

[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.