Derivative Instruments and Other Financial Instruments Used For Hedging (Details 1) (Cash Flow Hedges [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in OCI on Derivative Instruments (Effective Portion)	$ 28	$ (12)	$ 38	$ (7)
Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	3	(4)	5	(6)
Gain or (Loss) Recognized in Income on Derivative Instruments (Ineffective Portion and Amount Excluded from Effectiveness Testing)
Interest rate contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in OCI on Derivative Instruments (Effective Portion)	28	(12)	38	(7)
Interest income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	4	(3)	6	(4)
Interest expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(1)	(1)	(1)	(2)
Noninterest expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (Loss) Recognized in Income on Derivative Instruments (Ineffective Portion and Amount Excluded from Effectiveness Testing)