Loans Troubled Debt Restructurings (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013 contracts	Jun. 30, 2012 contracts	Jun. 30, 2013 contracts	Jun. 30, 2012 contracts
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Restructured, Payment Default During Peiriod, Number of Contracts	250	147	496	327
Financing Receivable, Restructured, Payment Default During Period, Amortized Cost at Default	$ 10	$ 17	$ 23	$ 36
Commercial and Industrial | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Restructured, Payment Default During Peiriod, Number of Contracts	19	14	42	25
Financing Receivable, Restructured, Payment Default During Period, Amortized Cost at Default	0	1	0	3
Commercial Real Estate | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Restructured, Payment Default During Peiriod, Number of Contracts	3	0	4	4
Financing Receivable, Restructured, Payment Default During Period, Amortized Cost at Default	0	0	3	4
Commercial Construction [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Restructured, Payment Default During Peiriod, Number of Contracts	0	4	1	7
Financing Receivable, Restructured, Payment Default During Period, Amortized Cost at Default	0	4	0	6
Residential Nonguaranteed [Member] | Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Restructured, Payment Default During Peiriod, Number of Contracts	80	28	156	56
Financing Receivable, Restructured, Payment Default During Period, Amortized Cost at Default	6	9	10	14
Home Equity | Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Restructured, Payment Default During Peiriod, Number of Contracts	52	38	101	81
Financing Receivable, Restructured, Payment Default During Period, Amortized Cost at Default	3	3	6	6
Residential Construction | Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Restructured, Payment Default During Peiriod, Number of Contracts	10	6	16	17
Financing Receivable, Restructured, Payment Default During Period, Amortized Cost at Default	0	0	2	2
Consumer Other Direct | Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Restructured, Payment Default During Peiriod, Number of Contracts	2	0	9	2
Financing Receivable, Restructured, Payment Default During Period, Amortized Cost at Default	0	0	0	0
Consumer Indirect | Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Restructured, Payment Default During Peiriod, Number of Contracts	49		88
Financing Receivable, Restructured, Payment Default During Period, Amortized Cost at Default	1		1
Consumer Credit Card | Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Restructured, Payment Default During Peiriod, Number of Contracts	35	57	79	135
Financing Receivable, Restructured, Payment Default During Period, Amortized Cost at Default	$ 0	$ 0	$ 1	$ 1