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		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Derivative [Line Items]
Amount of Gain (Loss) Reclassified from OCI to Consolidated Statement of Income	$ 2,598	$ 2,560	$ 5,083	$ 4,995
Derivatives designed as cash flow value hedges
Derivative [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Other Comprehensive Income	(53)	47	(66)	164
Amount of Gain (Loss) Reclassified from OCI to Consolidated Statement of Income	(1)	(1)	(2)	(2)
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	2	3	4	7
Interest-rate contracts | Derivatives designed as cash flow value hedges
Derivative [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Other Comprehensive Income	(1)	(1)	(2)	11
Interest-rate contracts | Net interest revenue | Derivatives designed as cash flow value hedges
Derivative [Line Items]
Amount of Gain (Loss) Reclassified from OCI to Consolidated Statement of Income	(1)	(1)	(2)	(2)
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	1	1	2	2
Foreign exchange contracts | Derivatives designed as cash flow value hedges
Derivative [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Other Comprehensive Income	(52)	48	(64)	153
Foreign exchange contracts | Net interest revenue | Derivatives designed as cash flow value hedges
Derivative [Line Items]
Amount of Gain (Loss) Reclassified from OCI to Consolidated Statement of Income	0	0	0	0
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	$ 1	$ 2	$ 2	$ 5