Management Contracts Purchased - Additional Information (Detail)	Dec. 31, 2022 USD ($) Funds	Sep. 30, 2022 USD ($)
Contracts In Progress Costs And Earnings [Line Items]
Number of mutual funds \| Funds	30
Management contracts impairment amount	$ 0	$ 0
Asset purchase	$ 43,000,000

The cash outflow for purchases of and capital improvements on property, plant and equipment (capital expenditures), software, and other intangible assets.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3213-108585

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 50
-Section 30
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=126928898&loc=d3e9212-128498

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 50
-Section 30
-Paragraph 2
-URI https://asc.fasb.org/extlink&oid=126928898&loc=d3e9215-128498

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 50
-Section 25
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=127000608&loc=d3e9135-128495

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