Financial Instruments and Fair Value Measurement - Fair Value Hierarchy (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	$ 57.7	$ 50.7
Trading securities	22.7	19.2
Deferred compensation plan liabilities	(22.7)	(19.2)
Derivatives:
Forward exchange contracts-(Liabilities)	(0.8)	(0.3)
Fair value, net asset (liability)	83.5	77.9
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	0.0	0.0
Trading securities	22.7	19.2
Deferred compensation plan liabilities	(22.7)	(19.2)
Derivatives:
Forward exchange contracts-(Liabilities)	0.0	0.0
Fair value, net asset (liability)	26.6	27.5
Quoted Prices in Active Markets for Similar Assets (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	57.7	50.7
Trading securities	0.0	0.0
Deferred compensation plan liabilities	0.0	0.0
Derivatives:
Forward exchange contracts-(Liabilities)	(0.8)	(0.3)
Fair value, net asset (liability)	56.9	50.4
Unobservable inputs for which little or no market data exists (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	0.0	0.0
Trading securities	0.0	0.0
Deferred compensation plan liabilities	0.0	0.0
Derivatives:
Forward exchange contracts-(Liabilities)	0.0	0.0
Fair value, net asset (liability)	0.0	0.0
Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents	26.6	27.5
Money Market Funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents	26.6	27.5
Money Market Funds | Quoted Prices in Active Markets for Similar Assets (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents	0.0	0.0
Money Market Funds | Unobservable inputs for which little or no market data exists (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and Cash Equivalents	$ 0.0	$ 0.0