Restricted Securities Available For Sale (Schedule Of Restricted Securities Available For Sale By Aging Category) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 Months	$ 2.2	$ 5.2
Gross Unrealized Losses, Less than 12 Months	0.0	0.0
Estimated Fair Value,12 Months or More	0.0	0.0
Gross Unrealized Losses, 12 Months or More	0.0	0.0
Total Estimated Fair Value	2.2	5.2
Total Gross Unrealized Losses	0.0	0.0
Corporate bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 Months	2.2	1.4
Gross Unrealized Losses, Less than 12 Months	0.0	0.0
Estimated Fair Value,12 Months or More	0.0	0.0
Gross Unrealized Losses, 12 Months or More	0.0	0.0
Total Estimated Fair Value	2.2	1.4
Total Gross Unrealized Losses	0.0	0.0
US Government and agency securities [Member]
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 Months	0.0	1.9
Gross Unrealized Losses, Less than 12 Months	0.0	0.0
Estimated Fair Value,12 Months or More	0.0	0.0
Gross Unrealized Losses, 12 Months or More	0.0	0.0
Total Estimated Fair Value	0.0	1.9
Total Gross Unrealized Losses	0.0	0.0
Asset-backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 Months	0.0	1.9
Gross Unrealized Losses, Less than 12 Months	0.0	0.0
Estimated Fair Value,12 Months or More	0.0	0.0
Gross Unrealized Losses, 12 Months or More	0.0	0.0
Total Estimated Fair Value	0.0	1.9
Total Gross Unrealized Losses	0.0	0.0
Mortgage-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less than 12 Months	0.0	0.0
Gross Unrealized Losses, Less than 12 Months	0.0	0.0
Estimated Fair Value,12 Months or More	0.0	0.0
Gross Unrealized Losses, 12 Months or More	0.0	0.0
Total Estimated Fair Value	0.0	0.0
Total Gross Unrealized Losses	$ 0.0	$ 0.0