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Investment Securities - Private Equity Funds and Hedge Funds (Details) - USD ($) $ in Millions | Mar. 31, 2024 | Dec. 31, 2023
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Total private equity funds and hedge funds included in other long-term investments |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Fair Value | $ 317.8 | $ 312.9
Unfunded Commitments | 52.7 | 57.7
Private equity funds |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Fair Value | 255.2 | 248.6
Unfunded Commitments | 52.7 | 57.7
Private equity funds | Aerospace/Defense/Government |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Fair Value | 163.5 | 157.2
Unfunded Commitments | 14.8 | 17.4
Private equity funds | Financial services |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Fair Value | 88.0 | 87.5
Unfunded Commitments | 35.5 | 37.8
Private equity funds | Real estate |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Fair Value | 3.7 | 3.9
Unfunded Commitments | 2.4 | 2.5
Hedge funds |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Fair Value | 62.6 | 64.3
Unfunded Commitments | 0.0 | 0.0
Hedge funds | Long/short equity financials and business services |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Fair Value | 57.7 | 54.4
Unfunded Commitments | 0.0 | 0.0
Hedge funds | European small/mid cap |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Fair Value | 4.9 | 9.9
Unfunded Commitments | $ 0.0 | $ 0.0

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