Restricted Securities Available For Sale (Schedule Of Restricted Securities Available For Sale By Aging Catagory) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Fair Value Less than 12 Months	$ 21.6	$ 23.4
Gross Unrealized Losses Less than 12 Months	(0.3)	(0.2)
Total Fair Value	21.6	23.4
Total Gross Unrealized Losses	(0.3)	(0.2)
US Government And Agency Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value Less than 12 Months	8.7	16.7
Gross Unrealized Losses Less than 12 Months	(0.2)	(0.1)
Total Fair Value	8.7	16.7
Total Gross Unrealized Losses	(0.2)	(0.1)
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value Less than 12 Months	9.5	2.8
Gross Unrealized Losses Less than 12 Months		(0.1)
Total Fair Value	9.5	2.8
Total Gross Unrealized Losses		(0.1)
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value Less than 12 Months	2.9	2.3
Gross Unrealized Losses Less than 12 Months	(0.1)
Total Fair Value	2.9	2.3
Total Gross Unrealized Losses	(0.1)
Certificates of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value Less than 12 Months	0.5	1.5
Total Fair Value	0.5	1.5
Foreign Government Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value Less than 12 Months		0.1
Total Fair Value		$ 0.1