Fair Value Measurement - Financial Assets and Liabilities by Hierarchy Level (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale investments	$ 44.4	$ 50.7
Trading securities	19.9	19.2
Deferred compensation plan liabilities	(19.9)	(19.2)
Derivatives:
Forward exchange contracts-Assets	0.8
Forward exchange contracts-(Liabilities)		(0.3)
TOTAL	356.1	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	19.9	19.2
Deferred compensation plan liabilities	(19.9)	(19.2)
Derivatives:
Forward exchange contracts-Assets	0.0
Forward exchange contracts-(Liabilities)		0.0
TOTAL	310.9	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	44.4	50.7
Trading securities	0.0	0.0
Deferred compensation plan liabilities	0.0	0.0
Derivatives:
Forward exchange contracts-Assets	0.8
Forward exchange contracts-(Liabilities)		(0.3)
TOTAL	45.2	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-Assets	0.0
Forward exchange contracts-(Liabilities)		0.0
TOTAL	0.0	0.0
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	310.9	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	310.9	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