CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net Income	$ 216.2	$ 157.3	$ 635.7	$ 471.5
Other comprehensive income, net of tax:
Foreign exchange translation adjustments	6.2	(5.1)	(0.4)	(2.2)
Income (loss) from derivative agreements	1.3	(7.2)	(23.7)	(24.9)
Other comprehensive income (loss)	7.5	(12.3)	(24.1)	(27.1)
Comprehensive income	$ 223.7	$ 145.0	$ 611.6	$ 444.4