Fair Value Disclosures (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012 Multiple		Mar. 31, 2011		Dec. 31, 2011
Fair value changes from valuation inputs or assumptions	$ 92		$ 40
Realization of the expected net servicing cash flows	(43)	[1]	(28)	[1]
Assets measured at fair value	29,736				28,932
Negative valuation adjustments of impaired loans	30		103
Negative valuation adjustments of foreclosed property	68		86
Fair value inputs earnings before interest taxes depreciation and amortization multiple lower range	4
Fair value inputs earnings before interest taxes depreciation and amortization multiple upper range	10
Fair Value, Measurements, Nonrecurring [Member]
Assets measured at fair value	680				925
Assets measured at fair value on a nonrecurring basis, impaired loans (excluding covered)	302				389
Assets measured at fair value on a nonrecurring basis, foreclosed real estate (excluding covered)	378				536
Mortgage Servicing Rights [Member]
Fair value changes from valuation inputs or assumptions	92		40
Realization of the expected net servicing cash flows	(43)		(28)
Income statement effect of changes in fair value produced gains/(losses)	$ (53)		$ (39)

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