CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Other comprehensive (loss) income:
Income tax expense (benefit) on translation adjustments on net investment hedge	$ 10.2	$ (34.3)	$ 8.4
Income tax expense (benefit) on unrealized gain (loss) on investments	0.0	(0.8)	0.4
Income tax expense (benefit) on defined benefit pension plans and retiree health care plan	$ 4.6	$ (0.1)	$ (5.8)