Consolidated Statements of Comprehensive Income (Unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Other comprehensive income (loss):
Income tax expense (benefit) on translation adjustments on net investment hedge	$ (9.3)	$ (3.2)	$ (31.0)	$ (8.8)
Income tax expense (benefit) on unrealized gain on investments	0.2	0.2	0.8	0.3
Income tax expense (benefit) on defined benefit pension plans and retiree health care plan	$ 0.1	$ (1.0)	$ 0.3	$ (1.3)