Derivatives and Hedging Activities - Fair Value of Derivative Instruments (Detail) € in Millions, $ in Millions	Dec. 31, 2018 USD ($)	Dec. 31, 2018 EUR (€)	Dec. 31, 2017 USD ($)
Derivatives Fair Value [Line Items]
Total Derivative Assets	$ 3.5		$ 4.1
Total Derivative Liabilities	(2.9)		(5.7)
Net Derivatives	0.6		(1.6)
Excludes debt designated as net investment hedge	3,236.5		3,230.5
Foreign Currency Forward Contracts
Derivatives Fair Value [Line Items]
Total Derivative Assets	3.5		4.1
Total Derivative Liabilities	(2.9)		(5.7)
Non-Designated as Hedging Instruments
Derivatives Fair Value [Line Items]
Total Derivative Assets	1.7		3.6
Total Derivative Liabilities	(2.7)		(3.3)
Net Derivatives	(1.0)		0.3
Non-Designated as Hedging Instruments | Foreign Currency Forward Contracts
Derivatives Fair Value [Line Items]
Total Derivative Assets	1.7		3.6
Total Derivative Liabilities	(2.7)		(3.3)
Designated as Hedging Instruments | Foreign Currency Forward Contracts
Derivatives Fair Value [Line Items]
Excludes debt designated as net investment hedge	454.9	€ 400.0	474.3
Cash Flow Hedge | Designated as Hedging Instruments
Derivatives Fair Value [Line Items]
Total Derivative Assets	1.8		0.5
Total Derivative Liabilities	(0.2)		(2.4)
Net Derivatives	1.6		(1.9)
Cash Flow Hedge | Designated as Hedging Instruments | Foreign Currency Forward Contracts
Derivatives Fair Value [Line Items]
Total Derivative Assets	1.8		0.5
Total Derivative Liabilities	$ (0.2)		$ (2.4)