Fair Value Disclosures (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Gains or losses recognized as a result of the transfer of securities during the period	$ 0		$ 0		$ 0
Venture Capital And Other Investments Probable Sale Less Than Net Asset Value	0
Due to changes in valuation inputs or assumptions	(341)		(138)		190
Realization of the expected net servicing cash flows	(151)	[1]	(129)	[1]	(126)	[1]
Income statement effect of changes in fair value produced gains	394		196		(98)
Assets measured at fair value	28,932		29,007	[2]
Assets measured at fair value on a nonrecurring basis, impaired loans (excluding covered)	389		705
Assets measured at fair value on a nonrecurring basis, foreclosed real estate (excluding covered)	536		1,300
Negative valuation adjustments of impaired loans	348		602
Negative valuation adjustments of foreclosed property	550		496
Fair Value, Measurements, Nonrecurring [Member]
Assets measured at fair value	$ 925		$ 2,000

[1] Represents the realization of expected net servicing cash flows, expected borrower payments and the passage of time.

[2] Excludes loans held for sale carried at the lower of cost or market.