Loan Servicing (Analysis of Activity in Residential Mortgage Servicing Rights) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011
Loan Servicing [Abstract]
Carrying value, beginning balance	$ 563		$ 830
Additions	134		126
Fair value changes from valuation inputs or assumptions	(38)		(20)
Other changes	(81)	[1]	(57)	[1]
Carrying value, ending balance	$ 578		$ 879

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