Fair Value Disclosures (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012		Sep. 30, 2011		Dec. 31, 2011
Fair value changes from valuation inputs or assumptions			$ (67)		$ (319)
Realization of the expected net servicing cash flows			(128)	[1]	(103)	[1]
Assets measured at fair value	30,701		30,701				28,932
Fair value inputs earnings before interest taxes depreciation and amortization multiple lower range			3
Fair value inputs earnings before interest taxes depreciation and amortization multiple upper range			12
Fair value inputs earnings before interest taxes depreciation and amortization multiple weighted average			7
Weighted average remaining life of private equity and similar investments			3
Fair Value, Measurements, Nonrecurring [Member]
Assets measured at fair value	309		309				925
Assets measured at fair value on a nonrecurring basis, impaired loans (excluding covered)	170		170				389
Assets measured at fair value on a nonrecurring basis, foreclosed real estate (excluding covered)	139		139				536
Negative valuation adjustments of impaired loans	27	71	82		293
Negative valuation adjustments of foreclosed property	45	103	181		274
Mortgage Servicing Rights [Member]
Fair value changes from valuation inputs or assumptions	(29)	(299)	(67)		(319)
Realization of the expected net servicing cash flows	(47)	(46)	(128)		(103)
Income statement effect of changes in fair value produced gains/(losses)	$ 49	$ 329	$ 148		$ 349

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