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Benefit Plans, Domestic and Foreign Pension Plan Assets and Summary of Defined Benefit Pension Plan Assets Measured at Fair Value (Details) - USD ($) $ in Millions | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
--- | --- | --- | ---
Fair value of plan assets [Abstract] |  |  |
Fair value of plan assets | $ 320.2 | $ 289.3 |
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] |  |  |
Fair value of plan assets [Abstract] |  |  |
Fair value of plan assets | 261.4 | 237.3 |
Significant Other Observable Inputs (Level 2) [Member] |  |  |
Fair value of plan assets [Abstract] |  |  |
Fair value of plan assets | 34.0 | 31.7 |
Significant Unobservable Inputs (Level 3) [Member] |  |  |
Fair value of plan assets [Abstract] |  |  |
Fair value of plan assets | 24.8 | 20.3 |
Equity Securities [Member] |  |  |
Fair value of plan assets [Abstract] |  |  |
Fair value of plan assets | 179.2 | 174.1 |
US Equities [Member] |  |  |
Fair value of plan assets [Abstract] |  |  |
Fair value of plan assets | 156.1 | 155.2 |
US Equities [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] |  |  |
Fair value of plan assets [Abstract] |  |  |
Fair value of plan assets | 156.1 | 155.0 |
US Equities [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Fair value of plan assets [Abstract] |  |  |
Fair value of plan assets | 0.0 | 0.2 |
US Equities [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Fair value of plan assets [Abstract] |  |  |
Fair value of plan assets | 0.0 | 0.0 |
Non-US Equities [Member] |  |  |
Fair value of plan assets [Abstract] |  |  |
Fair value of plan assets | 23.1 | 18.9 |
Non-US Equities [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] |  |  |
Fair value of plan assets [Abstract] |  |  |
Fair value of plan assets | 23.1 | 18.9 |
Non-US Equities [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Fair value of plan assets [Abstract] |  |  |
Fair value of plan assets | 0.0 | 0.0 |
Non-US Equities [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Fair value of plan assets [Abstract] |  |  |
Fair value of plan assets | 0.0 | 0.0 |
Fixed Income Securities [Member] |  |  |
Fair value of plan assets [Abstract] |  |  |
Fair value of plan assets | 116.0 | 94.7 |
Corporate Debt Instruments [Member] |  |  |
Fair value of plan assets [Abstract] |  |  |
Fair value of plan assets | 116.0 | 94.7 |
Corporate Debt Instruments [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] |  |  |
Fair value of plan assets [Abstract] |  |  |
Fair value of plan assets | 82.0 | 63.4 |
Corporate Debt Instruments [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Fair value of plan assets [Abstract] |  |  |
Fair value of plan assets | 34.0 | 31.3 |
Corporate Debt Instruments [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Fair value of plan assets [Abstract] |  |  |
Fair value of plan assets | 0.0 | 0.0 |
Real Estate [Member] |  |  |
Fair value of plan assets [Abstract] |  |  |
Fair value of plan assets | 2.4 | 1.9 |
Real Estate [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] |  |  |
Fair value of plan assets [Abstract] |  |  |
Fair value of plan assets | 0.0 | 0.0 |
Real Estate [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Fair value of plan assets [Abstract] |  |  |
Fair value of plan assets | 0.0 | 0.0 |
Real Estate [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Fair value of plan assets [Abstract] |  |  |
Fair value of plan assets | 2.4 | 1.9 |
Other [Member] |  |  |
Fair value of plan assets [Abstract] |  |  |
Fair value of plan assets | 22.6 | 18.6 |
Other [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] |  |  |
Fair value of plan assets [Abstract] |  |  |
Fair value of plan assets | 0.2 | 0.0 |
Other [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Fair value of plan assets [Abstract] |  |  |
Fair value of plan assets | 0.0 | 0.2 |
Other [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Fair value of plan assets [Abstract] |  |  |
Fair value of plan assets | 22.4 | 18.4 |
U.S. Plans [Member] |  |  |
Fair value of plan assets [Abstract] |  |  |
Fair value of plan assets | 241.9 | 221.9 | $ 213.0
International Plans [Member] |  |  |
Fair value of plan assets [Abstract] |  |  |
Fair value of plan assets | $ 78.3 | $ 67.4 | $ 69.5

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