Derivative Financial Instruments (Impact Of Derivatives On Consolidated Statement Of Income) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Derivatives not designated as hedging instruments
Derivative [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	$ 146	$ 129
Derivatives designated as fair value hedges
Derivative [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	(10)	39
Amount of Gain (Loss) on Hedged Item Recognized in Consolidated Statement of Income	10	(44)
Foreign exchange contracts | Trading services | Derivatives not designated as hedging instruments
Derivative [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	145	217
Foreign exchange contracts | Processing fees and other revenue | Derivatives not designated as hedging instruments
Derivative [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	0	(2)
Foreign exchange contracts | Processing fees and other revenue | Derivatives designated as fair value hedges
Derivative [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	4	30
Foreign exchange contracts | Processing fees and other revenue | Investment securities [Member] | Derivatives designated as fair value hedges
Derivative [Line Items]
Amount of Gain (Loss) on Hedged Item Recognized in Consolidated Statement of Income	(4)	(30)
Interest-rate contracts | Trading services | Derivatives not designated as hedging instruments
Derivative [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	1	(88)
Interest-rate contracts | Processing fees and other revenue | Derivatives not designated as hedging instruments
Derivative [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	0	2
Interest-rate contracts | Processing fees and other revenue | Contract one [Member] | Derivatives designated as fair value hedges
Derivative [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	(15)	(16)
Interest-rate contracts | Processing fees and other revenue | Contract two [Member] | Derivatives designated as fair value hedges
Derivative [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	1	25
Interest-rate contracts | Processing fees and other revenue | Long-term debt | Derivatives designated as fair value hedges
Derivative [Line Items]
Amount of Gain (Loss) on Hedged Item Recognized in Consolidated Statement of Income	16	13
Interest-rate contracts | Processing fees and other revenue | Investment securities available for sale | Derivatives designated as fair value hedges
Derivative [Line Items]
Amount of Gain (Loss) on Hedged Item Recognized in Consolidated Statement of Income	$ (2)	$ (27)