Loans TDR Modifications (Details) $ in Millions		12 Months Ended
		Dec. 31, 2018 USD ($) contracts		Dec. 31, 2017 USD ($) contracts		Dec. 31, 2016 USD ($) contracts
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		5,694	[1]	7,136	[2]	9,278	[3]
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		$ 28		$ 74		$ 93
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		238		299		389
Financing Receivable, Amount Restructured During Period		$ 266		$ 373		$ 482
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts	[1]	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
Commercial and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		169	[1]	178	[2]	84	[3]
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		$ 2		$ 3		$ 2
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		77		43		68
Financing Receivable, Amount Restructured During Period		$ 79		$ 46		$ 70
Residential Construction [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		4	[1]			1	[3]
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
Home Equity Line of Credit [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		525	[1]	2,488	[2]	2,611	[3]
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		$ 2		$ 45		$ 9
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		41		176		227
Financing Receivable, Amount Restructured During Period		$ 43		$ 221		$ 236
Residential Nonguaranteed [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		299	[1]	150	[2]	397	[3]
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		$ 19		$ 22		$ 79
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		52		10		12
Financing Receivable, Amount Restructured During Period		$ 71		$ 32		$ 91
Credit Card Receivable [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		1,410	[1]	919	[2]	720	[3]
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		$ 5		$ 4		$ 3
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		0		0		0
Financing Receivable, Amount Restructured During Period		$ 5		$ 4		$ 3
Consumer Indirect [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		2,585	[1]	2,740	[2]	1,539	[3]
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		58		61		32
Financing Receivable, Amount Restructured During Period		$ 58		$ 61		$ 32
Consumer Other Direct [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		701	[1]	661	[2]	3,925	[3],[4]
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		10		9		50	[4]
Financing Receivable, Amount Restructured During Period		$ 10		$ 9		$ 50	[4]
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, 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

[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 3,321 loans with a carrying value of $41 million that were modified prior to 2016 and reclassified as TDRs in the fourth quarter of 2016.