Investments in Affiliates -Summary of Transactions in, and Earnings from, Investments in Affiliates (Detail) - USD ($)	3 Months Ended			6 Months Ended
	Jun. 30, 2021		Jun. 30, 2020	Jun. 30, 2021		Jun. 30, 2020
Investments In And Advances To Affiliates [Line Items]
Beginning Value				$ 245,409,996
United States Treasury Obligations	$ (18,230)		$ (144,206)	(3,554)		$ (54,212)
Ending Value	283,470,722			283,470,722
Affiliated Investments [Member]
Investments In And Advances To Affiliates [Line Items]
Beginning Value	232,267,665		845,180,412	245,409,996		105,630,007
Purchases at Cost	135,306,617		496,692,333	448,948,844		1,375,683,621
Proceeds from Sales	(84,096,480)		(1,045,378,319)	(410,888,118)		(1,185,311,252)
United States Treasury Obligations	(7,080)		(295,230)			196,820
Ending Value	283,470,722		296,199,196	283,470,722		296,199,196
Dividend Income	13,773		457,439	35,325		1,169,671
Affiliated Investments [Member] | Exchange-Traded Fund [Member]
Investments In And Advances To Affiliates [Line Items]
Beginning Value	49,883,320		80,385,830	49,876,240	[1]	79,893,780
United States Treasury Obligations	(7,080)		(295,230)			196,820
Ending Value	49,876,240	[1]	80,090,600	49,876,240	[1]	80,090,600
Dividend Income	655		182,914	8,075		515,911
Affiliated Investments [Member] | Money Market Mutual Fund - Invesco Government & Agency Portfolio, Institutional Class [Member]
Investments In And Advances To Affiliates [Line Items]
Beginning Value			764,794,582			25,736,227
Purchases at Cost			496,692,333			1,375,683,621
Proceeds from Sales			(1,045,378,319)			(1,185,311,252)
Ending Value	233,594,482	[1],[2]	216,108,596	233,594,482	[1],[2]	216,108,596
Dividend Income			$ 274,525			$ 653,760
Affiliated Investments [Member] | Money Market Mutual Fund - Invesco Government & Agency Portfolio, Institutional Class [Member] | Money Market Mutual Fund - Invesco Premier U.S. Government Money ETF - Institutional Class [Member]
Investments In And Advances To Affiliates [Line Items]
Beginning Value	182,384,345			195,533,756
Purchases at Cost	135,306,617			448,948,844
Proceeds from Sales	(84,096,480)			(410,888,118)
Ending Value	233,594,482			233,594,482
Dividend Income	$ 13,118			$ 27,250

[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.

[2] The rate shown is the 7-day SEC standardized yield as of June 30, 2021.