CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net Income	$ 785.9	$ 615.9	$ 568.6
Other comprehensive income, net of tax:
Foreign exchange translation adjustments	10.4	5.7	(10.6)
Defined benefit plan adjustments gain (loss)	(0.0)	(0.9)	1.4
Income (loss) from derivative agreements	(21.3)	(17.9)	(7.4)
Other comprehensive (loss) income	(10.9)	(13.1)	(16.6)
Comprehensive income	$ 775.0	$ 602.8	$ 552.0