Significant Group Concentrations of Credit Risk (Outstanding Loans and Total Exposure from Loans of Automotive Industry) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Credit Risk [Line Items]
Total automotive exposure	$ 7,529	$ 7,536
Automotive Industry [Member]
Credit Risk [Line Items]
Total automotive loans	4,825	4,842
Automotive Production [Member]
Credit Risk [Line Items]
Minimum loan balance for inclusion	1
Total automotive loans	931	831
Total automotive exposure	1,698	1,778
Automotive Dealer [Member]
Credit Risk [Line Items]
Total automotive loans	3,894	4,011
Total automotive exposure	$ 5,831	$ 5,758