Loans TDR Modifications (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015 contracts		Mar. 31, 2014 contracts
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts	1,529	[1]	1,723	[1]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted	$ 4	[1],[2]	$ 3	[1],[3]
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted	34	[1],[2],[4]	43	[1],[3],[5]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted	48	[1]	58	[1]
Financing Receivable, Amount Restructured During Period	86	[1]	104	[1]
Commercial and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts	22	[1]	16	[1]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted	0		0
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted	0		0
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted	5	[1]	2	[1]
Financing Receivable, Amount Restructured During Period	5	[1]	2	[1]
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts			2	[1]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted			0
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted			0
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted			3	[1]
Financing Receivable, Amount Restructured During Period			3	[1]
Residential Nonguaranteed [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts	216	[1]	313	[1]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted	4	[1],[2]	3	[1],[3]
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted	30	[1],[2],[4]	39	[1],[3],[5]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted	7	[1]	19	[1]
Financing Receivable, Amount Restructured During Period	41	[1]	61	[1]
Home Equity Line of Credit [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts	468	[1]	433	[1]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted	0		0
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted	3	[1],[2],[4]	3	[1],[3],[5]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted	24	[1]	18	[1]
Financing Receivable, Amount Restructured During Period	27	[1]	21	[1]
Residential Construction [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts	1	[1]	6	[1]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted	0		0
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted	0		0
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted	0		0
Financing Receivable, Amount Restructured During Period	0		0
Consumer Other Direct [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts	17	[1]	17	[1]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted	0		0
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted	0		0
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted	0		0
Financing Receivable, Amount Restructured During Period	0		0
Consumer Indirect [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts	569	[1]	839	[1]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted	0		0
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted	0		0
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted	12	[1]	16	[1]
Financing Receivable, Amount Restructured During Period	12	[1]	16	[1]
Consumer Credit Card Financing Receivable [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts	236	[1]	97	[1]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted	0		0
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted	1	[1],[2],[4]	1	[1],[3],[5]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted	0		0
Financing Receivable, Amount Restructured During Period	$ 1	[1]	$ 1	[1]

[1] Includes loans modified under the terms of a TDR that were charged-off during the period.

[2] Restructured loans which had forgiveness of amounts contractually due under the terms of the loan typically have had multiple concessions including rate modifications and/or term extensions. The total amount of charge-offs associated with principal forgiveness during the three months ended March 31, 2015 was immaterial.

[3] Restructured loans which had forgiveness of amounts contractually due under the terms of the loan typically have had multiple concessions including rate modifications and/or term extensions. The total amount of charge-offs associated with principal forgiveness during the three months ended March 31, 2014 was immaterial.

[4] Restructured loans which had a modification of the loan's contractual interest rate may also have had an extension of the loan's contractual maturity date and/or other concessions. The financial effect of modifying the interest rate on the loans modified as a TDR was immaterial to the financial statements during the three months ended March 31, 2015.

[5] Restructured loans which had a modification of the loan's contractual interest rate may also have had an extension of the loan's contractual maturity date and/or other concessions. The financial effect of modifying the interest rate on the loans modified as a TDR was immaterial to the financial statements during the three months ended March 31, 2014.