Derivative Financial Instruments (Schedule Of Differences Between The Gains (Losses) On The Derivative And The Gains (Losses) On The Hedged Item) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Derivative [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Other Comprehensive Income	$ 1	$ 0
Amount of Gain (Loss) Reclassified from OCI to Consolidated Statement of Income	(2)	(2)
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	1	1
Net Interest Revenue [Member] | Derivatives Designated as Cash Flow Value Hedges [Member]
Derivative [Line Items]
Amount of Gain (Loss) Reclassified from OCI to Consolidated Statement of Income	(2)	(2)
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	1	1
Interest-Rate Contracts [Member] | Derivatives Designated as Cash Flow Value Hedges [Member]
Derivative [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Other Comprehensive Income	$ 1	$ 0