Income Taxes (Schedule of Components Of Income Tax Expense Benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Provisions for Income Taxes Recorded in the Consolidated Statements of Income [Abstract]
U.S. Federal, current expense	$ 109.7	$ 119.5	$ 77.3
State, current expense	29.1	28.8	18.2
Foreign, current expense	10.7	10.5	6.5
Total current expense	149.5	158.8	102.0
U.S. Federal, deferred expense benefit	11.9	(2.1)	(10.9)
State, deferred expense benefit	3.7	(0.6)	(3.2)
Foreign, deferred expense benefit	(0.2)	(0.3)
Total deferred expense (benefit)	15.4	(3.0)	(14.1)
Total income tax provision	$ 164.9	$ 155.8	$ 87.9