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Fair Value Measurements - Additional Information - Narrative (Details) | 12 Months Ended
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Dec. 31, 2024 USD ($) quotesPerInvestment | Dec. 31, 2023 USD ($) quotesPerInvestment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Quotes per fixed income investment | quotesPerInvestment | 3.0 | 2.9
Recurring |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Privately-held Investments, at fair value | $ 286,800,000 |
Recurring | Level 3 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Privately-held Investments, at fair value | 286,800,000 |
Total, Privately-held Investments | 311,000,000.0 |
Assets | Recurring | Level 3 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Transfers out of Level 3 |  | $ 12,100,000
Transfers Into Level 3 | 0 | 5,300,000
Settlements and sales | $ (239,700,000) | (137,200,000)
Equity Securities | Assets | Recurring | Level 3 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Transfers out of Level 3 |  | (6,600,000)
Transfers Into Level 3 |  | 0
Settlements and sales |  | $ 0

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