Credit Quality And Allowance For Credit Losses (Average Individually Evaluated Impaired Loans And Related Interest Recognized) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		$ 241	$ 322	$ 249	$ 383
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		3	3	6	7
Business loans | Commercial borrower
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		208	290	215	351
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		2	3	5	7
Business loans | Commercial borrower | Domestic loans
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		152	221	157	282
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		0	2	2	4
Business loans | Commercial borrower | International loans
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		3	5	3	5
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		0	0	0	0
Business loans | Commercial mortgage | Commercial borrower | Domestic loans
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		52	64	54	64
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		2	1	3	3
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Commercial Real Estate business line
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period	[1]	39	40	39	40
Individually Evaluated Impaired Loans Interest Income Recognized for the Period	[1]	1	1	2	3
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Other business lines
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period	[2]	13	24	15	24
Individually Evaluated Impaired Loans Interest Income Recognized for the Period	[2]	1	0	1	0
Retail loans
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		33	32	34	32
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		1	0	1	0
Retail loans | Consumer borrower
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		9	12	10	12
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		0	0	0	0
Retail loans | Residential mortgage
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		24	20	24	20
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		1	0	1	0
Retail loans | Home equity | Consumer borrower
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		9	11	9	11
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		0	0	0	0
Retail loans | Other consumer | Consumer borrower
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		0	1	1	1
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		0	0	0	0
Business Loans | Lease financing | Commercial borrower | Domestic loans
Financing Receivable, Impaired [Line Items]
Individually Evaluated Impaired Loans Average Balance for the Period		1	0	1	0
Individually Evaluated Impaired Loans Interest Income Recognized for the Period		$ 0	$ 0	$ 0	$ 0

[1] Primarily loans to real estate developers.

[2] Primarily loans secured by owner-occupied real estate.