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Investment Securities - Fair Value of Hedge Funds and Private Equity Funds (Details) - USD ($) $ in Millions | Jun. 30, 2021 | Dec. 31, 2020
--- | --- | ---
Hedge and private equity funds included in other long-term investments |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Fair Value | $ 142.3 | $ 121.2
Unfunded Commitments | 47.0 | 45.7
Private equity funds |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Fair Value | 129.2 | 121.2
Unfunded Commitments | 47.0 | 45.7
Private equity funds | Aerospace/Defense/Government |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Fair Value | 70.8 | 69.1
Unfunded Commitments | 14.0 | 15.3
Private equity funds | Financial services |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Fair Value | 54.0 | 23.5
Unfunded Commitments | 30.0 | 30.4
Private equity funds | Real Estate |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Fair Value | 4.3 | 0.0
Unfunded Commitments | 3.0 | 0.0
Private equity funds | Manufacturing/Industrial |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Fair Value | 0.1 | 28.6
Unfunded Commitments | 0.0 | 0.0
Hedge funds |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Fair Value | 13.1 | 0.0
Unfunded Commitments | 0.0 | 0.0
Hedge funds | European small/mid cap |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Fair Value | 13.1 | 0.0
Unfunded Commitments | $ 0.0 | $ 0.0

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