Loans TDR Modifications (Details) $ in Millions		3 Months Ended				9 Months Ended
		Sep. 30, 2019 USD ($) contracts	[1]	Sep. 30, 2018 USD ($) contracts	[2]	Sep. 30, 2019 USD ($) contracts	[3]	Sep. 30, 2018 USD ($) contracts
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		1,521		1,270		4,319		4,305	[4]
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		$ 5		$ 5		$ 14		$ 23	[4]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		36		50		89		207	[4]
Financing Receivable, Amount Restructured During Period		$ 41		$ 55		$ 103		$ 230	[4]
Residential Construction [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts	[4]							4
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
Credit Card [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		537		345		1,531		1,079	[4]
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		$ 3		$ 1		$ 7		$ 4	[4]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		0		0		0		0	[4]
Financing Receivable, Amount Restructured During Period		$ 3		$ 1		$ 7		$ 4	[4]
Commercial and Industrial [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		32		47		88		122	[4]
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		$ 0		$ 0		$ 1		$ 0	[4]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		12		16		17		75	[4]
Financing Receivable, Amount Restructured During Period		$ 12		$ 16		$ 18		$ 75	[4]
Residential Nonguaranteed [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		30		48		88		267	[4]
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		$ 2		$ 3		$ 4		$ 18	[4]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		2		7		7		46	[4]
Financing Receivable, Amount Restructured During Period		$ 4		$ 10		$ 11		$ 64	[4]
Home Equity Line of Credit [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		54		130		215		410	[4]
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		$ 0		$ 1		$ 2		$ 1	[4]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		3		11		13		34	[4]
Financing Receivable, Amount Restructured During Period		$ 3		$ 12		$ 15		$ 35	[4]
Consumer Other Direct [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		234		141		642		469	[4]
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		$ 0		$ 0		$ 0		$ 0	[4]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		3		2		10		6	[4]
Financing Receivable, Amount Restructured During Period		$ 3		$ 2		$ 10		$ 6	[4]
Consumer Indirect [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Restructured During Period, Number Of Contracts | contracts		634		559		1,755		1,954	[4]
Financing Receivable, Amount Restructured During Period, Rate Modifications Granted		$ 0		$ 0		$ 0		$ 0	[4]
Financing Receivable, Amount Restructured During Period, Term Extension and/or Other Concessions Granted		16		14		42		46	[4]
Financing Receivable, Amount Restructured During Period		$ 16		$ 14		$ 42		$ 46	[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.