Share-Based Compensation - Compensation Expense for Share-Based Awards (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense	$ 9.2	$ 8.4	$ 21.6	$ 20.1
Income tax benefit	(2.3)	(2.1)	(5.5)	(5.1)
Share-based compensation expense, net of tax benefit	6.9	6.3	16.1	15.0
Restricted Stock
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense	5.4	5.9	14.7	14.5
Performance Units
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense	$ 3.8	$ 2.5	$ 6.9	$ 5.6