Investments in Affiliates - Summary of Transactions in, and Earnings from, Investments in Affiliates (Detail) - USD ($)		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Investments In And Advances To Affiliates [Line Items]
Beginning Value		$ 86,041,269
Change in Unrealized Appreciation (Depreciation)		(3,869)	$ (14,796)	$ 6,114
Ending Value		79,239,151	86,041,269
Exchange Traded Funds
Investments In And Advances To Affiliates [Line Items]
Beginning Value	[1]	17,435,550
Ending Value	[1]	11,439,187	17,435,550
Affiliated Investments [Member]
Investments In And Advances To Affiliates [Line Items]
Beginning Value		86,041,269	63,714,072
Purchases at Cost		161,384,878	459,054,104
Proceeds from Sales		(168,181,581)	(436,675,982)
Change in Unrealized Appreciation (Depreciation)		12,478	(50,925)
Realized Gain (Loss)		15,954	7,156
Ending Value		79,239,151	86,041,269	63,714,072
Dividend Income		19,848	288,312
Affiliated Investments [Member] | Invesco Government & Agency Portfolio, Institutional Class [Member]
Investments In And Advances To Affiliates [Line Items]
Beginning Value		68,605,719
Purchases at Cost		161,384,878	146,871,130
Proceeds from Sales		(162,190,633)	(78,265,411)
Ending Value		67,799,964	68,605,719
Dividend Income		17,024	2,810
Affiliated Investments [Member] | Money Market Mutual Fund - Invesco Government and Agency Portfolio - Institutional Class [Member]
Investments In And Advances To Affiliates [Line Items]
Beginning Value			63,714,072	8,547,404
Purchases at Cost			294,696,499	371,336,542
Proceeds from Sales			(358,410,571)	(316,169,874)
Ending Value				63,714,072
Dividend Income			244,278	$ 195,656
Affiliated Investments [Member] | Exchange Traded Funds
Investments In And Advances To Affiliates [Line Items]
Beginning Value		17,435,550
Purchases at Cost			17,486,475
Proceeds from Sales		(5,990,948)
Change in Unrealized Appreciation (Depreciation)		12,478	(50,925)
Realized Gain (Loss)		15,954	7,156
Ending Value		11,439,187	17,435,550
Dividend Income		$ 2,824	$ 41,224

[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.