Fair Value Disclosures (Narrative) (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		Dec. 31, 2011
Fair value changes from valuation inputs or assumptions			$ (38)		$ (20)
Realization of the expected net servicing cash flows			(81)	[1]	(57)	[1]
Assets measured at fair value	30,791		30,791				28,932
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
Weighted average remaining life of private equity and similar investments			2
Fair Value, Measurements, Nonrecurring [Member]
Assets measured at fair value	430		430				925
Assets measured at fair value on a nonrecurring basis, impaired loans (excluding covered)	209		209				389
Assets measured at fair value on a nonrecurring basis, foreclosed real estate (excluding covered)	221		221				536
Negative valuation adjustments of impaired loans	25	119	55		222
Negative valuation adjustments of foreclosed property	68	85	136		171
Mortgage Servicing Rights [Member]
Fair value changes from valuation inputs or assumptions	(130)	(60)	(38)		(20)
Realization of the expected net servicing cash flows	(38)	(29)	(81)		(57)
Income statement effect of changes in fair value produced gains/(losses)	$ 152	$ 59	$ 99		$ 20

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