Loans TDR Modifications (Details) $ in Millions		12 Months Ended
		Dec. 31, 2015 USD ($) contracts		Dec. 31, 2014 USD ($) contracts		Dec. 31, 2013 USD ($) contracts
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		6,391	[1]	6,656	[2]	8,774	[3]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted		$ 12	[1],[4]	$ 14	[2],[5]	$ 19	[3],[6]
Financing Receivables, Impaired, Troubled Debt Restructuring, Write-down		2		14		2
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		164	[1]	138	[2]	270	[3]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		199	[1]	228	[2]	346	[2],[3]
Financing Receivable, Amount Restructured During Period		$ 375	[1]	$ 380	[2]	$ 635	[3]
Commercial and Industrial Sector [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		79	[1]	78	[2]	152	[3]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted		$ 0		$ 0		$ 18	[3],[6]
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		1	[1]	1	[2]	2	[3]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		8	[1]	37	[2]	105	[3]
Financing Receivable, Amount Restructured During Period		$ 9	[1]	$ 38	[2]	$ 125	[3]
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		1	[1]	6	[2]	6	[3]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted		$ 0		$ 4	[2],[5]	$ 0
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		0		0		3	[3]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		0		3	[2]	1	[3]
Financing Receivable, Amount Restructured During Period		$ 0		$ 7	[2]	$ 4	[3]
Commercial Construction [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts	[3]					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	[3]					$ 0
Residential Nonguaranteed [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		789	[1]	1,135	[2]	1,584	[3]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted		$ 12	[1],[4]	$ 10	[2],[5]	$ 1	[3],[6]
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		129	[1]	127	[2]	166	[3]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		25	[1]	44	[2]	94	[3]
Financing Receivable, Amount Restructured During Period		$ 166	[1]	$ 181	[2]	$ 261	[3]
Home Equity Line of Credit [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		2,172	[1]	1,977	[2]	2,630	[3]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted		$ 0		$ 0		$ 0
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		25	[1]	7	[2]	71	[3]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		113	[1]	86	[2]	75	[3]
Financing Receivable, Amount Restructured During Period		$ 138	[1]	$ 93	[2]	$ 146	[3]
Residential Construction [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		23	[1]	11	[2]	259	[3]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted		$ 0		$ 0		$ 0
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		6	[1]	1	[2]	24	[3]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		0		0		3	[3]
Financing Receivable, Amount Restructured During Period		$ 6	[1]	$ 1	[2]	$ 27	[3]
Consumer Other Direct [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		66	[1]	71	[2]	140	[3]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted		$ 0		$ 0		$ 0
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		0		0		1	[3]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		1	[1]	1	[2]	3	[3]
Financing Receivable, Amount Restructured During Period		$ 1	[1]	$ 1	[2]	$ 4	[3]
Consumer Indirect [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		2,578	[1]	2,928	[2]	3,409	[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		52	[1]	57	[2]	65	[3]
Financing Receivable, Amount Restructured During Period		$ 52	[1]	$ 57	[2]	$ 65	[3]
Credit Card Receivable [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		683	[1]	450	[2]	593	[3]
Financing Receivable, Amount Restructured During Period, Principal Forgiveness Granted		$ 0		$ 0		$ 0
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		3	[1]	2	[2]	3	[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]	$ 2	[2]	$ 3	[3]

[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, 2015 was

[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, 2014 was $14 million.

[6] 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, 2013 was $2 million.