Loans TDR Modifications (Details) $ in Millions		12 Months Ended
		Dec. 31, 2016 USD ($) contracts		Dec. 31, 2015 USD ($) contracts		Dec. 31, 2014 USD ($) contracts
Financing Receivable, Modifications [Line Items]
Financing Receivables, Impaired, Troubled Debt Restructuring, Write-down				$ 2		$ 14
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		12,472	[1]	6,391	[2]	6,656	[3]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted		$ 3	[1],[4]	$ 12	[2],[5]	$ 14	[3],[6]
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		97	[1]	164	[2]	138	[3]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		474	[1]	199	[2]	228	[3]
Financing Receivable, Amount Restructured During Period		$ 574	[1]	$ 375	[2]	$ 380	[3]
Commercial and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		144	[1]	79	[2]	78	[3]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted		$ 0		$ 0		$ 0
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		2	[1]	1	[2]	1	[3]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		134	[1]	8	[2]	37	[3]
Financing Receivable, Amount Restructured During Period		$ 136	[1]	$ 9	[2]	$ 38	[3]
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		4	[1]	1	[2]	6	[3]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted		$ 0		$ 0		$ 4	[3],[6]
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		0		0		0
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		0		0		3	[3]
Financing Receivable, Amount Restructured During Period		$ 0		$ 0		$ 7	[3]
Commercial Construction [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts	[1]	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		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		931	[1]	789	[2]	1,135	[3]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted		$ 3	[1],[4]	$ 12	[2],[5]	$ 10	[3],[6]
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		82	[1]	129	[2]	127	[3]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		10	[1]	25	[2]	44	[3]
Financing Receivable, Amount Restructured During Period		$ 95	[1]	$ 166	[2]	$ 181	[3]
Home Equity Line of Credit [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		3,448	[1]	2,172	[2]	1,977	[3]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted		$ 0		$ 0		$ 0
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		10	[1]	25	[2]	7	[3]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		243	[1]	113	[2]	86	[3]
Financing Receivable, Amount Restructured During Period		$ 253	[1]	$ 138	[2]	$ 93	[3]
Residential Construction [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		63	[1]	23	[2]	11	[3]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted		$ 0		$ 0		$ 0
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		0	[1]	6	[2]	1	[3]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		0		0		0
Financing Receivable, Amount Restructured During Period		$ 0	[1]	$ 6	[2]	$ 1	[3]
Consumer Other Direct [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		4,021	[1],[7]	66	[2]	71	[3]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted		$ 0		$ 0		$ 0
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		0		0		0
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		50	[1],[7]	1	[2]	1	[3]
Financing Receivable, Amount Restructured During Period		$ 50	[1],[7]	$ 1	[2]	$ 1	[3]
Consumer Indirect [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		3,141	[1]	2,578	[2]	2,928	[3]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted		$ 0		$ 0		$ 0
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		0		0		0
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		37	[1]	52	[2]	57	[3]
Financing Receivable, Amount Restructured During Period		$ 37	[1]	$ 52	[2]	$ 57	[3]
Credit Card Receivable [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		719	[1]	683	[2]	450	[3]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted		$ 0		$ 0		$ 0
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		3	[1]	3	[2]	2	[3]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		0		0		0
Financing Receivable, Amount Restructured During Period		$ 3	[1]	$ 3	[2]	$ 2	[3]
Loans modified prior to 2016 [Member] | Consumer Other Direct [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		3,321
Financing Receivable, Amount Restructured During Period		$ 41

[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] 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 year ended December 31, 2016 was immaterial.

[5] 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 year ended December 31, 2015 was $2 million.

[6] 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 year ended December 31, 2014 was $14 million.

[7] Includes 3,321 loans with an amortized cost of $41 million that were modified prior to 2016 and reclassified as TDRs in the fourth quarter of 2016.