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Investment Securities - Investments In Private Equity Funds Subject to Lock-Up Periods (Details) - USD ($) $ in Millions | Mar. 31, 2024 | Dec. 31, 2023
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Debt and Equity Securities, FV-NI [Line Items] |  |
1 – 3 years | $ 14.4 |
3 – 5 years | 63.5 |
5 – 10 years | 161.0 |
>10 years | 16.3 |
Total | 1,991.9 | $ 1,998.2
Private equity funds |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Total | $ 255.2 |

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