Investments in Affiliates -Summary of Transactions in, and Earnings from, Investments in Affiliates (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			$ 105,630,007
United States Treasury Obligations	$ 8,761	$ (41,398)	(45,451)		$ 60,905
Ending Value	620,888,813		620,888,813
Affiliated Investments [Member]
Investments In And Advances To Affiliates [Line Items]
Beginning Value	296,199,196	101,954,188	105,630,007		102,216,801
Purchases at Cost	744,677,740	159,197,124	2,120,361,361		638,558,101
Proceeds from Sales	(419,935,133)	(164,077,025)	(1,605,246,385)		(643,817,950)
United States Treasury Obligations	(52,990)	(15,140)	143,830		102,195
Ending Value	620,888,813	97,059,147	620,888,813		97,059,147
Dividend Income	71,137	541,140	1,240,808		1,728,345
Affiliated Investments [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	216,108,596	22,018,773	25,736,227		22,398,721
Purchases at Cost	190,622,258	159,197,124	1,566,305,879		638,558,101
Proceeds from Sales	(406,730,854)	(164,077,025)	(1,592,042,106)		(643,817,950)
Ending Value		17,138,872			17,138,872
Dividend Income	11,735	99,673	665,495		346,738
Affiliated Investments [Member] | Exchange-Traded Fund [Member]
Investments In And Advances To Affiliates [Line Items]
Beginning Value	80,090,600	79,935,415	79,893,780	[1]	79,818,080
United States Treasury Obligations	(52,990)	(15,140)	143,830		102,195
Ending Value	80,037,610	79,920,275	80,037,610		79,920,275
Dividend Income	58,024	$ 441,467	573,935		$ 1,381,607
Affiliated Investments [Member] | Money Market Mutual Fund - Invesco Government & Agency Portfolio, Institutional Class [Member]
Investments In And Advances To Affiliates [Line Items]
Purchases at Cost	554,055,482		554,055,482
Proceeds from Sales	(13,204,279)		(13,204,279)
Ending Value	540,851,203		540,851,203
Dividend Income	$ 1,378		$ 1,378

[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.