Loans and ACL (Summary of the pre-default balance for modifications that experienced a payment default) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Commercial and Industrial, Excluding Covered [Member]
Financing Receivable, Modifications [Line Items]
Modifications that defaulted during the period that had been classified as a TDR during the previous 12 months	$ 2	$ 0	$ 5	$ 4
CRE - Other, Excluding Covered [Member]
Financing Receivable, Modifications [Line Items]
Modifications that defaulted during the period that had been classified as a TDR during the previous 12 months	5	1	11	6
CRE - Residential ADC, Excluding Covered [Member]
Financing Receivable, Modifications [Line Items]
Modifications that defaulted during the period that had been classified as a TDR during the previous 12 months	0	1	4	13
Direct Retail Lending, Excluding Covered [Member]
Financing Receivable, Modifications [Line Items]
Modifications that defaulted during the period that had been classified as a TDR during the previous 12 months	1	3	3	7
Retail Revolving Credit, Excluding Covered [Member]
Financing Receivable, Modifications [Line Items]
Modifications that defaulted during the period that had been classified as a TDR during the previous 12 months	3	3	8	9
Retail Residential Mortgage, Excluding Covered [Member]
Financing Receivable, Modifications [Line Items]
Modifications that defaulted during the period that had been classified as a TDR during the previous 12 months	3	6	15	30
Retail Sales Finance, Excluding Covered [Member]
Financing Receivable, Modifications [Line Items]
Modifications that defaulted during the period that had been classified as a TDR during the previous 12 months	0	0	1	0
Retail Other Lending Subsidiaries, Excluding Covered [Member]
Financing Receivable, Modifications [Line Items]
Modifications that defaulted during the period that had been classified as a TDR during the previous 12 months	$ 10	$ 5	$ 22	$ 8