Derivatives and Hedging Activities - Fair Value of Derivative Instruments (Details) € in Millions, $ in Millions	Jun. 30, 2018 USD ($)	Jun. 30, 2018 EUR (€)	Dec. 31, 2017 USD ($)
Derivatives not designated as hedging instruments:
Total Derivative Assets	$ 4.7		$ 4.1
Total Derivative Liabilities	(4.7)		(5.7)
Net Derivatives	0.0		(1.6)
Long-term debt, less current portion	3,217.1		3,230.5
Foreign currency forward contracts
Derivatives not designated as hedging instruments:
Total Derivative Assets	4.7		4.1
Total Derivative Liabilities	(4.7)		(5.7)
Designated as Hedging Instruments | Foreign currency forward contracts
Derivatives not designated as hedging instruments:
Long-term debt, less current portion	459.6	€ 400.0	474.3
Designated as Hedging Instruments | Cash Flow
Derivatives not designated as hedging instruments:
Total Derivative Assets	1.5		0.5
Total Derivative Liabilities	0.0		(2.4)
Net Derivatives	1.5		(1.9)
Designated as Hedging Instruments | Cash Flow | Foreign currency forward contracts
Derivatives not designated as hedging instruments:
Total Derivative Assets	1.5		0.5
Total Derivative Liabilities	0.0		(2.4)
Non-Designated
Derivatives not designated as hedging instruments:
Total Derivative Assets	3.2		3.6
Total Derivative Liabilities	(4.7)		(3.3)
Net Derivatives	(1.5)		0.3
Non-Designated | Foreign currency forward contracts
Derivatives not designated as hedging instruments:
Total Derivative Assets	3.2		3.6
Total Derivative Liabilities	$ (4.7)		$ (3.3)