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		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 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	$ 1	$ 1	$ 3
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	6	2	6
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	0	4	0	5
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	1	2
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	2	5	5
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	6	4	13	12
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	1	0	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	$ 7	$ 6	$ 16	$ 12