Derivative Financial Instruments (Schedule Of Differences Between The Gains (Losses) On The Derivative And The Gains (Losses) On The Hedged Item) (Details) (Derivatives Designated as Cash Flow Value Hedges [Member], USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Amount of Gain (Loss) on Derivative Recognized in Other Comprehensive Income	$ 4	$ 1	$ 8	$ 6
Amount of Gain (Loss) Reclassified from OCI to Consolidated Statement of Income	(1)	(2)	(5)	(5)
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income		2	2	4
Interest-Rate Contracts [Member]
Amount of Gain (Loss) on Derivative Recognized in Other Comprehensive Income	4	1	8	6
Net Interest Revenue [Member]
Amount of Gain (Loss) Reclassified from OCI to Consolidated Statement of Income	(1)	(2)	(5)	(5)
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income		$ 2	$ 2	$ 4