Fair Value Measurement - Financial Assets and Liabilities by Hierarchy Level (Details) - USD ($) $ in Millions		Jun. 30, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	[1]	$ 221.4	$ 263.5
Available for sale investments		58.2	57.4
Trading securities		12.7	10.2
Deferred compensation plan liabilities		(12.7)	(10.2)
Derivatives:
Forward exchange contracts-Assets	[2]	0.0	0.8
Forward exchange contracts-(Liabilities)	[3]	(0.7)	(0.1)
TOTAL		278.9	321.6
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	[1]	221.4	263.5
Available for sale investments		0.0	0.0
Trading securities		12.7	10.2
Deferred compensation plan liabilities		(12.7)	(10.2)
Derivatives:
Forward exchange contracts-Assets	[2]	0.0	0.0
Forward exchange contracts-(Liabilities)	[3]	0.0	0.0
TOTAL		221.4	263.5
Quoted Prices in Active Markets for Similar Assets (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	[1]	0.0	0.0
Available for sale investments		54.2	53.6
Trading securities		0.0	0.0
Deferred compensation plan liabilities		0.0	0.0
Derivatives:
Forward exchange contracts-Assets	[2]	0.0	0.8
Forward exchange contracts-(Liabilities)	[3]	(0.7)	(0.1)
TOTAL		53.5	54.3
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]
Money market funds	[1]	0.0	0.0
Available for sale investments		4.0	3.8
Trading securities		0.0	0.0
Deferred compensation plan liabilities		0.0	0.0
Derivatives:
Forward exchange contracts-Assets	[2]	0.0	0.0
Forward exchange contracts-(Liabilities)	[3]	0.0	0.0
TOTAL		$ 4.0	$ 3.8

[1] (a) Money market funds are reflected in Cash and cash equivalents in the Condensed Consolidated Balance Sheet.

[2] (b) Forward exchange contracts-Assets are reflected in Other current assets in the Condensed Consolidated Balance Sheet.

[3] (c) Forward exchange contracts-(Liabilities) are reflected in Other accrued liabilities in the Condensed Consolidated Balance Sheet.