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v3.25.3

Investments, at Fair Value - Narrative (Details) | 3 Months Ended | 6 Months Ended | 12 Months Ended
--- | --- | --- | ---
Sep. 30, 2025 USD ($) underlying_investment investment_fund | Sep. 30, 2024 USD ($) | Sep. 30, 2025 USD ($) underlying_investment investment_fund | Sep. 30, 2024 USD ($) | Mar. 31, 2025 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |
Return of investments in alternative assets held by Customer ExAlt Trusts |  |  | $ 7,780,000 | $ 12,547,000 | $ 47,800,000
Income (loss) from equity method investments |  |  | $ 11,800,000 |  |
Alternative investment funds | investment_fund | 188 |  | 188 |  |
Underlying investments | underlying_investment | 522 |  | 522 |  |
Percent of underlying investments in private companies | 85.00% |  | 85.00% |  |
Unrealized gain (loss) on investments in available-for-sale debt securities | $ 92,000 | $ 26,000 | $ 92,000 | 5,000 |
Debt securities, available-for-sale, loss | 0 | 500,000 | 0 | 1,000,000.0 |
Equity securities without readily determinable fair value | 26,500,000 |  | 26,500,000 |  | 26,500,000
Equity impairment loss | 0 | $ 0 | 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 | $ 4,400,000 |  | $ 4,400,000 |  | $ 4,100,000

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