Fair Value Measurements - Fair Value of Hedges (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative designated as hedging instrument	$ 3.9		$ 5.0
Interest rate swap
Derivatives, Fair Value [Line Items]
Derivative designated as hedging instrument	(3.8)	$ 0.0	(5.7)	$ (2.8)
Interest rate swap | Other assets/(accrued liabilities)
Derivatives, Fair Value [Line Items]
Derivative fair value	7.6		7.6		$ (0.2)
Derivative designated as hedging instrument	5.0		7.6
Cross-currency interest rate swaps | Other assets
Derivatives, Fair Value [Line Items]
Derivative fair value	2.8		2.8		$ 0.0
Derivative designated as hedging instrument	$ 23.6		$ 2.8