Marketable Securities (Schedule Of Amount Related To Credit Losses Recognized In Earnings For Other-Than-Temporary Impairments) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Marketable Securities [Abstract]
Beginning balance of amounts related to credit losses, January 1, 2013	$ 0.3	$ 2.2	$ 2.7
Reductions for securities sold in the period for which OTTI was previously recognized	(0.1)	(1.9)	(0.5)
Ending balance of amounts related to credit losses, September 30, 2013	$ 0.2	$ 0.3	$ 2.2