CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net Income	$ 568.6	$ 743.4	$ 459.0
Other comprehensive income, net of tax:
Foreign exchange translation adjustments	(10.6)	18.4	(11.5)
Defined benefit plan adjustments gain (loss)	1.4	12.6	(1.7)
Income (loss) from derivative agreements	(7.4)	(3.6)	(4.7)
Other comprehensive (loss) income	(16.6)	27.4	(17.9)
Comprehensive income	$ 552.0	$ 770.8	$ 441.1