Investments - Summary of Investments (Detail) - USD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024
Schedule of Investments [Line Items]
Total investments	$ 174.8	$ 177.4
Non Marketable Equity Securities
Schedule of Investments [Line Items]
Total investments	124.1	124.1
Seed Capital Investments
Schedule of Investments [Line Items]
Total investments	25.9	23.1
Marketable Equity Securities
Schedule of Investments [Line Items]
Total investments	19.8	21.6
Partnership Interests in Private Equity Funds
Schedule of Investments [Line Items]
Total investments	$ 5.0	$ 8.6

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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