Loans TDR Modifications (Details) $ in Millions		3 Months Ended				9 Months Ended
		Sep. 30, 2017 USD ($) contracts	[1]	Sep. 30, 2016 USD ($) contracts		Sep. 30, 2017 USD ($) contracts	[3]	Sep. 30, 2016 USD ($) contracts
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		1,868		1,192	[2]	5,300		4,170	[4]
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		$ 27		$ 23	[2]	$ 40		$ 91	[4]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		75		116	[2]	322		319	[4]
Financing Receivable, Amount Restructured During Period		$ 102		$ 139	[2]	$ 362		$ 410	[4]
Commercial and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		76		19	[2]	136		48	[4]
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		$ 2		$ 0		$ 2		$ 0	[4]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		7		49	[2]	86		95	[4]
Financing Receivable, Amount Restructured During Period		$ 9		$ 49	[2]	$ 88		$ 95	[4]
Commercial Construction [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts	[4]							1
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted	[4]							$ 0
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted	[4]							0
Financing Receivable, Amount Restructured During Period	[4]							$ 0
Residential Nonguaranteed [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		41		102	[2]	119		339	[4]
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		$ 6		$ 22	[2]	$ 17		$ 80	[4]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		4		3	[2]	8		11	[4]
Financing Receivable, Amount Restructured During Period		$ 10		$ 25	[2]	$ 25		$ 91	[4]
Home Equity Line of Credit [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		696		569	[2]	1,971		2,030	[4]
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		$ 18		$ 0	[2]	$ 18		$ 9	[4]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		45		55	[2]	172		182	[4]
Financing Receivable, Amount Restructured During Period		$ 63		$ 55	[2]	$ 190		$ 191	[4]
Consumer Other Direct [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		135		2	[2]	425		34	[4]
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		$ 0		$ 0	[2]	$ 0		$ 0	[4]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		2		0	[2]	6		1	[4]
Financing Receivable, Amount Restructured During Period		$ 2		$ 0	[2]	$ 6		$ 1	[4]
Consumer Indirect [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		738		351	[2]	2,034		1,217	[4]
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		$ 0		$ 0	[2]	$ 0		$ 0	[4]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		17		9	[2]	50		30	[4]
Financing Receivable, Amount Restructured During Period		$ 17		$ 9	[2]	$ 50		$ 30	[4]
Credit Card Receivable [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		182		149	[2]	615		501	[4]
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		$ 1		$ 1	[2]	$ 3		$ 2	[4]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		0		0	[2]	0		0	[4]
Financing Receivable, Amount Restructured During Period		$ 1		$ 1	[2]	$ 3		$ 2	[4]

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

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