v3.26.1
Investments, at Fair Value - Narrative (Details)
 12 Months Ended
Mar. 31, 2026
USD ($)
security
underlyingInvestment
investmentFund
Mar. 31, 2025
USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Income (loss) from equity method investments   $ (96,300,000)
Proceeds from limited partnership investments   51,500,000
Proceeds from equity method investment, distribution   12,100,000
Equity securities without readily determinable fair value, downward price adjustment, cumulative amount   49,500,000
Payments to acquire equity method investments   14,800,000
Noncontrolling interest, increase from subsidiary equity issuance   2,200,000
Alternative investment funds | investmentFund 140  
Underlying investments | underlyingInvestment 397  
Percent of underlying investments in private companies 98.00%  
Unrealized gain (loss) $ 100,000 (300,000)
Debt securities, available-for-sale, allowance for credit loss, period increase (decrease) 0 (1,000,000.0)
Other equity securities and interests 26,500,000 26,500,000
Equity impairment loss $ 0 0
Number of securities with an upward adjustment | security 1  
Equity securities, cumulative upward adjustment $ 10,800,000  
Equity securities, upward adjustment 0 0
Other Public Companies | Class A common stock, par value $0.001 per share    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Fair value of common stock $ 4,500,000 $ 4,100,000