Marketable Securities (Schedule Of Marketable Securities With Gross Unrealized Losses For Which Other-Than-Temporary Impairment Has Been Incurred) (Details) (Marketable Securities With OTTI Incurred [Member], USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	$ 0.1
12 Months or More, Fair Value	0
Total, Fair Value	0.1
Less than 12 Months, Unrealized Loss	0
12 Months or More, Unrealized Loss	0
Total, Unrealized Loss	0
Asset-Backed And Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months, Fair Value	0.1
12 Months or More, Fair Value	0
Total, Fair Value	0.1
Less than 12 Months, Unrealized Loss	0
12 Months or More, Unrealized Loss	0
Total, Unrealized Loss	$ 0