Credit Loss Reserves (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Allowance for Loan and Lease Losses [Roll Forward]
Credit loss reserves at beginning of period	$ 5,865	$ 4,944	$ 5,952	$ 5,512
Provision for credit losses	738	583	1,529	1,291
Net charge-offs:
Charge-offs	(799)	(1,078)	(1,778)	(2,495)
Recoveries	102	141	203	282
Total net charge-offs	(697)	(937)	(1,575)	(2,213)
Reserves on receivables transferred to held for sale	(1,298)		(1,298)
Credit loss reserves at end of period	$ 4,608	$ 4,590	$ 4,608	$ 4,590