Income Taxes (Difference In Income Tax Expense And Expected Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
U.S. federal statutory income tax rate	21.00%	21.00%	21.00%
U.S. federal income tax expense at statutory rate	$ 253.6	$ 237.9	$ 219.2
State income taxes, net of federal benefit	34.9	36.3	32.8
Other, net	(5.7)	(0.6)	0.8
Total income tax expense	$ 282.8	$ 273.6	$ 252.8
Effective income tax rate	23.40%	24.20%	24.20%