Consolidated Statements of Comprehensive Income (Unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Other comprehensive income (loss):
Income tax expense (benefit) on translation adjustments on net investment hedge	$ (18.4)	$ 6.4	$ (21.7)	$ (5.6)
Income tax expense (benefit) on unrealized gain on investments	0.1	0.2	0.6	0.1
Income tax expense (benefit) on defined benefit pension plans and retiree health care plan	$ 0.2	$ 0.0	$ 0.2	$ (0.3)