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