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Investments - Summary of Investments (Detail) - USD ($)
$ in Millions
Mar. 31, 2025
Dec. 31, 2024
Schedule of Investments [Line Items]    
Total investments $ 174.0 $ 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 23.0 23.1
Marketable Equity Securities    
Schedule of Investments [Line Items]    
Total investments 18.5 21.6
Partnership Interests in Private Equity Funds    
Schedule of Investments [Line Items]    
Total investments $ 8.4 $ 8.6