Purchased Impaired Loans (Narrative) (Details) (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Financing Receivable, Impaired [Line Items]
Provision for credit losses (benefit)	$ 261	$ 486	$ 962	$ 2,060
Charge-offs recorded on impaired loans			1,782	2,568
Specific allowance for loan and lease losses associated with purchased impaired loans	986		986
Purchased impaired loans	6,927	8,130	6,927	8,130	7,780
Purchased Impaired Loans [Member]
Financing Receivable, Impaired [Line Items]
Provision for credit losses (benefit)			216
Charge-offs recorded on impaired loans			127
Impaired Loans With Associated Allowance [Member]
Financing Receivable, Impaired [Line Items]
Purchased impaired loans	6,600		6,600
Impaired Loans Without Associated Allowance [Member]
Financing Receivable, Impaired [Line Items]
Purchased impaired loans	$ 300		$ 300