CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement Of Income And Comprehensive Income [Abstract]
Net Income	$ 230.4	$ 216.2	$ 669.4	$ 635.7
Other comprehensive income, net of tax:
Foreign exchange translation adjustments	(5.1)	6.2	(4.7)	(0.4)
Defined benefit plan adjustments gain (loss)	(0.0)	(0.0)	(0.7)	(0.0)
Income (loss) from derivative agreements	10.0	1.3	22.1	(23.7)
Other comprehensive income (loss)	4.9	7.5	16.7	(24.1)
Comprehensive income	$ 235.3	$ 223.7	$ 686.1	$ 611.6