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Investment Securities - Private Equity Funds and Hedge Funds (Details) - USD ($) $ in Millions | Sep. 30, 2024 | Dec. 31, 2023
--- | --- | ---
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 | $ 349.0 | $ 312.9
Unfunded Commitments | 85.3 | 57.7
Private equity funds |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Fair Value | 262.0 | 248.6
Unfunded Commitments | 85.3 | 57.7
Private equity funds | Aerospace/Defense/Government |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Fair Value | 169.0 | 157.2
Unfunded Commitments | 46.8 | 17.4
Private equity funds | Financial services |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Fair Value | 89.3 | 87.5
Unfunded Commitments | 36.1 | 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 | 87.0 | 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 | 56.5 | 54.4
Unfunded Commitments | 0.0 | 0.0
Hedge funds | Long/short all cap global |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |
Fair Value | 30.5 | 0.0
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 | 0.0 | 9.9
Unfunded Commitments | $ 0.0 | $ 0.0

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