Stock-Based Compensation (Schedule Of Financial Information Of Options) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Employee Stock Option
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested in Period, Fair Value	$ 6.0	$ 6.0	$ 5.0
Share-Based Payment Arrangement, Expense	4.1	4.2	4.2
Share-Based Payment Arrangement, Expense, Tax Benefit	1.1	1.1	1.1
Share-Based Payment Arrangement, Amount Capitalized	1.9	1.7	1.5
Restricted Stock Units (RSUs) [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-Based Payment Arrangement, Expense	2.8	2.0	1.9
Share-Based Payment Arrangement, Expense, Tax Benefit	0.7	0.5	0.5
Share-Based Payment Arrangement, Amount Capitalized	1.2	0.8	0.7
Restricted Stock [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-Based Payment Arrangement, Expense	22.2	23.2	24.7
Share-Based Payment Arrangement, Expense, Tax Benefit	5.7	5.9	6.3
Share-Based Payment Arrangement, Amount Capitalized	9.7	9.2	9.3
Long Term Performance Unit [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-Based Payment Arrangement, Expense	11.1	16.0	14.5
Share-Based Payment Arrangement, Expense, Tax Benefit	2.8	4.1	3.7
Share-Based Payment Arrangement, Amount Capitalized	$ 5.2	$ 6.7	$ 5.8