Fair Value Disclosures (Fair Value and Unpaid Principal Balance of Loans Held for Sale) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Loans held for sale at fair value	$ 3,467		$ 3,736
Fair Value [Member]
Loans held for sale at fair value	3,467	[1]	3,736	[1]
Aggregate Unpaid Principal Balance [Member]
Loans held for sale at fair value	3,314	[1]	3,652	[1]
Fair Value Less Aggregate Unpaid Principal Balance [Member]
Loans held for sale at fair value	$ 153	[1]	$ 84	[1]

[1] The change in fair value is reflected in mortgage banking income. Excluding government guaranteed loans, there were no nonaccrual loans or loans 90 days or more past due and still accruing interest.