Derivative Financial Instruments and Fair Value Measurements (Details) $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2017 EUR (€)	Dec. 31, 2016 USD ($)
Net investment hedges [Abstract]
Translation gain (loss) on net investment hedge	$ 19.1			$ 24.8
Fair value measured on a recurring basis
Assets
Deferred compensation plan assets	91.5			86.8
Foreign currency forward contracts	0.1
Total assets measured at fair value	91.6			86.8
Liabilities
Foreign currency forward contracts				0.2
Total liabilities measured at fair value				0.2
Fair value measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Deferred compensation plan assets	91.5			86.8
Foreign currency forward contracts	0.0
Total assets measured at fair value	91.5			86.8
Liabilities
Foreign currency forward contracts				0.0
Total liabilities measured at fair value				0.0
Fair value measured on a recurring basis | Significant Other Observable Inputs (Level 2)
Assets
Deferred compensation plan assets	0.0			0.0
Foreign currency forward contracts	0.1
Total assets measured at fair value	0.1			0.0
Liabilities
Foreign currency forward contracts				0.2
Total liabilities measured at fair value				0.2
Fair value measured on a recurring basis | Significant Unobservable Inputs (Level 3)
Assets
Deferred compensation plan assets	0.0			0.0
Foreign currency forward contracts	0.0
Total assets measured at fair value	0.0			0.0
Liabilities
Foreign currency forward contracts				0.0
Total liabilities measured at fair value				0.0
Euro-denominated notes
Net investment hedges [Abstract]
Translation gain (loss) on net investment hedge	23.3			29.0
Forward contracts | Designated as hedging instrument
Net investment hedges [Abstract]
Translation gain (loss) on net investment hedge	(4.2)			(4.2)
Forward contracts | Not designated as hedging instrument
Net investment hedges [Abstract]
Gain associated with forward contracts included in interest and other expenses	0.1
Loss associated with forward contracts included in interest and other expenses		$ 0.6
Fair value | Euro-denominated notes | Significant Other Observable Inputs (Level 2)
Liabilities
Carrying value of long-term debt	840.9			831.6
Carrying value | Euro-denominated notes
Liabilities
Carrying value of long-term debt	795.6			$ 785.2
Notes due June 2018 | Euro-denominated notes | Designated as hedging instrument
Net investment hedges [Abstract]
Long-term debt	372.4		€ 350,000,000.0
Notes due September 2022 | Euro-denominated notes | Designated as hedging instrument
Net investment hedges [Abstract]
Long-term debt	$ 423.2		€ 400,000,000