Loans TDR Modifications (Details) $ in Millions		3 Months Ended
		Mar. 31, 2016 USD ($) contracts		Mar. 31, 2015 USD ($) contracts
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		1,543	[1]	1,529	[2]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted	[2],[3]			$ 4
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		$ 39	[1]	34	[2]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		69	[1]	48	[2]
Financing Receivable, Amount Restructured During Period		$ 108	[1]	$ 86	[2]
Commercial and Industrial Sector [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		12	[1]	22	[2]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted				$ 0
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		$ 0	[1]	0	[2]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		2	[1]	5	[2]
Financing Receivable, Amount Restructured During Period		$ 2	[1]	$ 5	[2]
Commercial Construction [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		1
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		$ 0
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		0
Financing Receivable, Amount Restructured During Period		$ 0
Residential Nonguaranteed [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		120	[1]	216	[2]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted	[2],[3]			$ 4
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		$ 31	[1]	30	[2]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		3	[1]	7	[2]
Financing Receivable, Amount Restructured During Period		$ 34	[1]	$ 41	[2]
Home Equity Line of Credit [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		732	[1]	468	[2]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted				$ 0
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		$ 7	[1]	3	[2]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		52	[1]	24	[2]
Financing Receivable, Amount Restructured During Period		$ 59	[1]	$ 27	[2]
Residential Construction [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts	[2]			1
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted				$ 0
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted	[2]			0
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted				0
Financing Receivable, Amount Restructured During Period	[2]			$ 0
Consumer Other Direct [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		23	[1]	17	[2]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted				$ 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		1	[1]	0	[2]
Financing Receivable, Amount Restructured During Period		$ 1	[1]	$ 0	[2]
Consumer Indirect [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		486	[1]	569	[2]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted				$ 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		11	[1]	12	[2]
Financing Receivable, Amount Restructured During Period		$ 11	[1]	$ 12	[2]
Credit Card Receivable [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		169	[1]	236	[2]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted				$ 0
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		$ 1	[1]	1	[2]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		0		0
Financing Receivable, Amount Restructured During Period		$ 1	[1]	$ 1	[2]

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

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

[3] Restructured loans which had forgiveness of amounts contractually due under the terms of the loan may have had other 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.