Restricted Securities Available For Sale (Schedule Of Restricted Securities Available For Sale By Aging Category) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value Less than 12 Months	$ 26.0	$ 23.4
Gross Unrealized Losses Less than 12 Months	(0.3)	(0.2)
Estimated Fair Value 12 Months or More
Gross Unrealized Losses 12 Months or More
Total Estimated Fair Value	26.0	23.4
Total Gross Unrealized Losses	(0.3)	(0.2)
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value Less than 12 Months	10.0	2.8
Gross Unrealized Losses Less than 12 Months		(0.1)
Estimated Fair Value 12 Months or More
Gross Unrealized Losses 12 Months or More
Total Estimated Fair Value	10.0	2.8
Total Gross Unrealized Losses		(0.1)
US Government And Agency Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value Less than 12 Months	11.8	16.7
Gross Unrealized Losses Less than 12 Months	(0.2)	(0.1)
Estimated Fair Value 12 Months or More
Gross Unrealized Losses 12 Months or More
Total Estimated Fair Value	11.8	16.7
Total Gross Unrealized Losses	(0.2)	(0.1)
Certificates of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value Less than 12 Months	1.9	1.5
Estimated Fair Value 12 Months or More
Gross Unrealized Losses 12 Months or More
Total Estimated Fair Value	1.9	1.5
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value Less than 12 Months	2.3	2.3
Gross Unrealized Losses Less than 12 Months	(0.1)
Estimated Fair Value 12 Months or More
Gross Unrealized Losses 12 Months or More
Total Estimated Fair Value	2.3	2.3
Total Gross Unrealized Losses	(0.1)
Foreign Government Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value Less than 12 Months		0.1
Estimated Fair Value 12 Months or More
Gross Unrealized Losses 12 Months or More
Total Estimated Fair Value		$ 0.1