Loans Troubled Debt Restructurings (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014 contracts	Jun. 30, 2013 contracts	Jun. 30, 2014 contracts	Jun. 30, 2013 contracts
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Restructured, Payment Default During Peiriod, Number of Contracts	197	250	366	496
Financing Receivable, Restructured, Payment Default During Period, Amortized Cost at Default	$ 13	$ 10	$ 20	$ 23
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Restructured, Payment Default During Peiriod, Number of Contracts	22	19	47	42
Financing Receivable, Restructured, Payment Default During Period, Amortized Cost at Default	4	0	5	0
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Restructured, Payment Default During Peiriod, Number of Contracts		3		4
Financing Receivable, Restructured, Payment Default During Period, Amortized Cost at Default		0		3
Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Restructured, Payment Default During Peiriod, Number of Contracts		0		1
Financing Receivable, Restructured, Payment Default During Period, Amortized Cost at Default		0		0
Residential Nonguaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Restructured, Payment Default During Peiriod, Number of Contracts	40	80	89	156
Financing Receivable, Restructured, Payment Default During Period, Amortized Cost at Default	6	6	10	10
Home Equity Line of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Restructured, Payment Default During Peiriod, Number of Contracts	24	52	47	101
Financing Receivable, Restructured, Payment Default During Period, Amortized Cost at Default	2	3	3	6
Residential Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Restructured, Payment Default During Peiriod, Number of Contracts	2	10	6	16
Financing Receivable, Restructured, Payment Default During Period, Amortized Cost at Default	0	0	0	2
Consumer Other Direct [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Restructured, Payment Default During Peiriod, Number of Contracts	0	2	5	9
Financing Receivable, Restructured, Payment Default During Period, Amortized Cost at Default	0	0	0	0
Consumer Indirect [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Restructured, Payment Default During Peiriod, Number of Contracts	46	49	89	88
Financing Receivable, Restructured, Payment Default During Period, Amortized Cost at Default	0	1	1	1
Consumer Credit Card Financing Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Restructured, Payment Default During Peiriod, Number of Contracts	63	35	83	79
Financing Receivable, Restructured, Payment Default During Period, Amortized Cost at Default	$ 1	$ 0	$ 1	$ 1