CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 150.7	$ 143.6	$ 95.6
Other comprehensive (loss) income, net of tax:
Foreign currency translation adjustments	68.8	(18.1)	(70.3)
Prior service credit arising during period, net of tax of $1.1 and $0.3	0.0	1.9	0.4
Net actuarial gain (loss) arising during period, net of tax of $1.3, $(4.8) and $(6.0)	6.3	(11.1)	(9.3)
Settlement effects arising during period, net of tax of $1.1 and $18.7	0.0	2.0	31.7
Less: amortization of actuarial loss, net of tax of $0.5, $1.2 and $1.6	3.6	2.2	2.9
Less: amortization of prior service credit, net of tax of $(0.5), $(0.5) and $(0.5)	(3.5)	(0.9)	(0.8)
Less: amortization of transition obligation	0.0	0.1	0.1
Net (loss) gain on investment securities, net of tax of $(2.5), $(0.1) and $0.4	(4.7)	(0.2)	0.7
Net (loss) gain on derivatives, net of tax of $(0.1), $0.1 and $0.8	(1.0)	(0.1)	1.2
Other comprehensive income (loss), net of tax	69.5	(24.2)	(43.4)
Comprehensive income	$ 220.2	$ 119.4	$ 52.2