Fair Value Measurements - Fair Value of Hedges (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative designated as hedging instrument	$ 4.2		$ 9.2
Interest rate swap
Derivatives, Fair Value [Line Items]
Derivative designated as hedging instrument	(3.3)	$ (0.8)	(9.0)	$ (3.6)
Interest rate swap | Other assets/(accrued liabilities)
Derivatives, Fair Value [Line Items]
Derivative fair value	11.8		11.8		$ (0.2)
Derivative designated as hedging instrument	4.2		11.8
Cross-currency interest rate swaps | Other assets
Derivatives, Fair Value [Line Items]
Derivative fair value	6.1		6.1		$ 0.0
Derivative designated as hedging instrument	$ 3.3		$ 6.1