Share-Based Compensation - Allocation of Compensation Expense by Plan (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Share-Based Compensation
Total share-based compensation (benefit) expense before tax	$ (2.4)	$ 24.6	$ 42.0	$ 93.8
Stock options
Share-Based Compensation
Total share-based compensation (benefit) expense before tax	5.7	5.8	16.8	19.8
RSUs
Share-Based Compensation
Total share-based compensation (benefit) expense before tax	9.9	6.2	23.6	18.4
STAP awards
Share-Based Compensation
Total share-based compensation (benefit) expense before tax	(18.5)	12.2	0.2	54.3
ESPP
Share-Based Compensation
Total share-based compensation (benefit) expense before tax	$ 0.5	$ 0.4	$ 1.4	$ 1.3