Restricted Securities Available For Sale (Schedule Of Cost And Estimated Fair Values Of Debt Securities By Contractual Maturity) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Restricted Securities Available For Sale [Abstract]
Within one year, cost	$ 39.0	$ 33.8
Over one year to five years, cost	9.1	8.6
Over five years to ten years, cost	4.1	3.9
Total restricted securities available for sale, cost	52.2	46.3
Within one year, estimated fair value	39.0	33.7
Over one year to five years, estimated fair value	9.0	8.6
Over five years to ten years, estimated fair value	3.9	3.8
Total restricted securities available for sale, estimated fair value	$ 51.9	$ 46.1