Restricted Securities Available For Sale (Schedule Of Cost And Estimated Fair Values Of Debt Securities By Contractual Maturity) (Details) - USD ($) $ in Millions		Dec. 31, 2022	Dec. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Within one year, cost		$ 4.0	$ 2.9
Over one year to five years, cost		66.4	56.9
Over five years to ten years, cost		5.6	2.1
Over ten years, cost		0.1	0.1
Total restricted securities available for sale, cost		76.1	62.0
Within one year, estimated fair value		3.9	3.0
Over one year to five years, estimated fair value		63.0	57.0
Over five years to ten years, estimated fair value		5.3	2.0
Over ten years, fair value		0.1	0.1
Debt Securities, Available-for-sale, Restricted	[1]	$ 72.3	$ 62.1

[1] Measured at fair value on a recurring basis.