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Employee Benefit Plans - Fair Value Measurement of Plan Assets (Details) - USD ($) $ in Millions | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
--- | --- | --- | ---
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 190.2 | $ 174.9 | $ 183.4
Cash/Money Markets |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 4.5 | 4.6 |
Foreign Government/Treasury Securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 19.4 | 17.3 |
Corporate Bonds, Debentures |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 35.3 | 33.3 |
Equity Securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 40.4 | 32.3 |
Mutual Funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 8.0 | 7.3 |
Investment and Insurance Annuity Contracts |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 82.6 | 80.1 |
Quoted Prices in Active Markets for Identical Assets (Level 1) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 23.9 | 21.9 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Cash/Money Markets |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 4.5 | 4.6 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Foreign Government/Treasury Securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 19.4 | 17.3 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate Bonds, Debentures |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0.0 | 0.0 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity Securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0.0 | 0.0 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Mutual Funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0.0 | 0.0 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Investment and Insurance Annuity Contracts |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0.0 | 0.0 |
Significant Observable Inputs (Level 2) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 114.3 | 102.4 |
Significant Observable Inputs (Level 2) | Cash/Money Markets |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0.0 | 0.0 |
Significant Observable Inputs (Level 2) | Foreign Government/Treasury Securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0.0 | 0.0 |
Significant Observable Inputs (Level 2) | Corporate Bonds, Debentures |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 35.3 | 33.3 |
Significant Observable Inputs (Level 2) | Equity Securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 40.4 | 32.3 |
Significant Observable Inputs (Level 2) | Mutual Funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 8.0 | 7.3 |
Significant Observable Inputs (Level 2) | Investment and Insurance Annuity Contracts |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 30.6 | 29.5 |
Significant Unobservable Inputs (Level 3) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 52.0 | 50.6 |
Significant Unobservable Inputs (Level 3) | Cash/Money Markets |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0.0 | 0.0 |
Significant Unobservable Inputs (Level 3) | Foreign Government/Treasury Securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0.0 | 0.0 |
Significant Unobservable Inputs (Level 3) | Corporate Bonds, Debentures |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0.0 | 0.0 |
Significant Unobservable Inputs (Level 3) | Equity Securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0.0 | 0.0 |
Significant Unobservable Inputs (Level 3) | Mutual Funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0.0 | 0.0 |
Significant Unobservable Inputs (Level 3) | Investment and Insurance Annuity Contracts |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 52.0 | $ 50.6 | $ 55.2

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