Loans Troubled Debt Restructurings (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014 contracts	Sep. 30, 2013 contracts	Sep. 30, 2014 contracts	Sep. 30, 2013 contracts
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Restructured, Payment Default During Peiriod, Number of Contracts	212	242	578	738
Financing Receivable, Restructured, Payment Default During Period, Amortized Cost at Default	$ 10	$ 13	$ 30	$ 35
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Restructured, Payment Default During Peiriod, Number of Contracts	30	3	77	45
Financing Receivable, Restructured, Payment Default During Period, Amortized Cost at Default	3	0	8	0
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Restructured, Payment Default During Peiriod, Number of Contracts		0		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	46	63	135	219
Financing Receivable, Restructured, Payment Default During Period, Amortized Cost at Default	6	9	16	19
Home Equity Line of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Restructured, Payment Default During Peiriod, Number of Contracts	28	37	75	138
Financing Receivable, Restructured, Payment Default During Period, Amortized Cost at Default	1	2	4	8
Residential Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Restructured, Payment Default During Peiriod, Number of Contracts	0	26	6	42
Financing Receivable, Restructured, Payment Default During Period, Amortized Cost at Default	0	1	0	2
Consumer Other Direct [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Restructured, Payment Default During Peiriod, Number of Contracts	3	5	8	14
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	45	55	134	143
Financing Receivable, Restructured, Payment Default During Period, Amortized Cost at Default	0	1	1	2
Consumer Credit Card Financing Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Restructured, Payment Default During Peiriod, Number of Contracts	60	53	143	132
Financing Receivable, Restructured, Payment Default During Period, Amortized Cost at Default	$ 0	$ 0	$ 1	$ 1