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, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
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	$ 1	$ 2	$ 2	$ 5
CRE Income Producing Properties, 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	5	1	11
CRE Construction And Development, 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	3	4
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	1	2	3
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	2	3	7	8
Retail Residential Mortgage-Nonguaranteed, 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	7	3	20	15
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	1
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	$ 9	$ 10	$ 24	$ 22