Investments in Affiliates - Summary of Transactions in, and Earnings from, Investments in Affiliates (Detail) - USD ($)	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Investments In And Advances To Affiliates [Line Items]
Beginning Value	$ 31,507,548
Change in Unrealized Appreciation (Depreciation)	(164)	$ 6,597
Ending Value	33,478,674
Affiliated Entity \| Money Market Mutual Fund - Invesco Premier U.S. Government Money Portfolio - Institutional Class [Member]
Investments In And Advances To Affiliates [Line Items]
Beginning Value	31,507,548	53,676,948
Purchases at Cost	13,571,361	30,618,756
Proceeds from Sales	(11,600,235)	(48,588,332)
Ending Value	33,478,674	35,707,372
Dividend Income	$ 5,511	$ 3,843

Value of the investment at close of period. For investment in and advances to affiliates, if operations of any controlled companies are different in character from those of the company, group such affiliates within divisions and by type of activities.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 6
-Subparagraph (SX 210.12-14(3))
-URI http://asc.fasb.org/extlink&oid=122147990&loc=d3e611322-123010

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 6
-Subparagraph (SX 210.12-14(2))
-URI http://asc.fasb.org/extlink&oid=122147990&loc=d3e611322-123010

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 6
-Subparagraph (SX 210.12-14(Column E))
-URI http://asc.fasb.org/extlink&oid=122147990&loc=d3e611322-123010

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Gross additions to the investment in and advance to the affiliate.

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At the close of the period, the dividends or interest included in caption 1 of the statement of operations. In addition, show as the final item the aggregate of dividends and interest included in the statement of operations in respect of investments in affiliates not held at the close of the period. The total of this column would be expected to agree with the correlative amount shown on the related statement of operations.

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Amount of unrealized gain (loss) on investment in marketable security.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
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