Derivatives and Hedging Activities - Fair Value of Derivative Instruments (Details) € in Millions, $ in Millions	Mar. 31, 2018 EUR (€)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Derivatives not designated as hedging instruments:
Total Derivative Assets		$ 7.9	$ 4.1
Total Derivative Liabilities		(10.2)	(5.7)
Net Derivatives		(2.3)	(1.6)
Long-term debt, less current portion		3,247.9	3,230.5
Foreign currency forward contracts
Derivatives not designated as hedging instruments:
Total Derivative Assets		7.9	4.1
Total Derivative Liabilities		(10.2)	(5.7)
Designated as Hedging Instruments | Foreign currency forward contracts
Derivatives not designated as hedging instruments:
Long-term debt, less current portion	€ 400.0	488.7	474.3
Designated as Hedging Instruments | Cash Flow
Derivatives not designated as hedging instruments:
Total Derivative Assets		0.7	0.5
Total Derivative Liabilities		(1.0)	(2.4)
Net Derivatives		(0.3)	(1.9)
Designated as Hedging Instruments | Cash Flow | Foreign currency forward contracts
Derivatives not designated as hedging instruments:
Total Derivative Assets		0.7	0.5
Total Derivative Liabilities		(1.0)	(2.4)
Non-Designated
Derivatives not designated as hedging instruments:
Total Derivative Assets		7.2	3.6
Total Derivative Liabilities		(9.2)	(3.3)
Net Derivatives		(2.0)	0.3
Non-Designated | Foreign currency forward contracts
Derivatives not designated as hedging instruments:
Total Derivative Assets		7.2	3.6
Total Derivative Liabilities		$ (9.2)	$ (3.3)