Credit Quality And Allowance For Credit Losses (Aging Analysis Of Loans) (Details) - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		$ 446	$ 153
Nonaccrual loans		235	199
Current loans		52,777	50,017
Total loans		53,458	50,369
30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		345	80
60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		37	47
90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		64	26
Business loans | Commercial borrower
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		399	122
Nonaccrual loans		193	162
Current loans		48,730	45,800
Total loans		49,322	46,084
Business loans | Commercial borrower | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		302	59
Business loans | Commercial borrower | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		33	37
Business loans | Commercial borrower | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		64	26
Business loans | Commercial borrower | Domestic loans
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		288	51
Nonaccrual loans		173	148
Current loans		33,788	31,274
Total loans		34,249	31,473
Business loans | Commercial borrower | Domestic loans | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		224	27
Business loans | Commercial borrower | Domestic loans | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		22	7
Business loans | Commercial borrower | Domestic loans | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		42	17
Business loans | Commercial borrower | International loans
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		18	5
Nonaccrual loans		0	0
Current loans		1,017	1,004
Total loans		1,035	1,009
Business loans | Commercial borrower | International loans | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		14	0
Business loans | Commercial borrower | International loans | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	5
Business loans | Commercial borrower | International loans | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		4	0
Business loans | Real estate construction | Commercial borrower | Domestic loans
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		5	13
Nonaccrual loans		0	0
Current loans		3,751	3,442
Total loans		3,756	3,455
Business loans | Real estate construction | Commercial borrower | Domestic loans | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		4	6
Business loans | Real estate construction | Commercial borrower | Domestic loans | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		1	7
Business loans | Real estate construction | Commercial borrower | Domestic loans | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	0
Business loans | Real estate construction | Commercial borrower | Domestic loans | Commercial Real Estate business line
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[1]	5	6
Nonaccrual loans	[1]	0	0
Current loans	[1]	3,341	3,038
Total loans	[1]	3,346	3,044
Business loans | Real estate construction | Commercial borrower | Domestic loans | Commercial Real Estate business line | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[1]	4	6
Business loans | Real estate construction | Commercial borrower | Domestic loans | Commercial Real Estate business line | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[1]	1	0
Business loans | Real estate construction | Commercial borrower | Domestic loans | Commercial Real Estate business line | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[1]	0	0
Business loans | Real estate construction | Commercial borrower | Domestic loans | Other business lines
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[2]	0	7
Nonaccrual loans	[2]	0	0
Current loans	[2]	410	404
Total loans	[2]	410	411
Business loans | Real estate construction | Commercial borrower | Domestic loans | Other business lines | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[2]	0	0
Business loans | Real estate construction | Commercial borrower | Domestic loans | Other business lines | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[2]	0	7
Business loans | Real estate construction | Commercial borrower | Domestic loans | Other business lines | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[2]	0	0
Business loans | Commercial mortgage | Commercial borrower | Domestic loans
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		88	52
Nonaccrual loans		19	14	[2]
Current loans		9,591	9,493
Total loans		9,698	9,559
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		60	25
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		10	18
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		18	9
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Commercial Real Estate business line
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[1]	9	9
Nonaccrual loans	[1]	3	2
Current loans	[1]	2,167	2,165
Total loans	[1]	2,179	2,176
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Commercial Real Estate business line | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[1]	1	9
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Commercial Real Estate business line | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[1]	0	0
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Commercial Real Estate business line | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[1]	8	0
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Other business lines
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[2]	79	43
Nonaccrual loans	[2]	16	12
Current loans	[2]	7,424	7,328
Total loans	[2]	7,519	7,383
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Other business lines | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[2]	59	16
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Other business lines | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[2]	10	18
Business loans | Commercial mortgage | Commercial borrower | Domestic loans | Other business lines | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing	[2]	10	9
Business loans | Lease financing | Commercial borrower | Domestic loans
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	1
Nonaccrual loans		1	0
Current loans		583	587
Total loans		584	588
Business loans | Lease financing | Commercial borrower | Domestic loans | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	1
Business loans | Lease financing | Commercial borrower | Domestic loans | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	0
Business loans | Lease financing | Commercial borrower | Domestic loans | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	0
Retail loans
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		47	31
Nonaccrual loans		42	37
Current loans		4,047	4,217
Total loans		4,136	4,285
Retail loans | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		43	21
Retail loans | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		4	10
Retail loans | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	0
Retail loans | Consumer borrower
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		7	14
Nonaccrual loans		22	17
Current loans		2,286	2,409
Total loans		2,315	2,440
Retail loans | Consumer borrower | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		6	6
Retail loans | Consumer borrower | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		1	8
Retail loans | Consumer borrower | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	0
Retail loans | Residential mortgage
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		40	17
Nonaccrual loans		20	20
Current loans		1,761	1,808
Total loans		1,821	1,845
Retail loans | Residential mortgage | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		37	15
Retail loans | Residential mortgage | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		3	2
Retail loans | Residential mortgage | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	0
Retail loans | Home equity | Consumer borrower
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		6	9
Nonaccrual loans		22	17
Current loans		1,699	1,685
Total loans		1,727	1,711
Retail loans | Home equity | Consumer borrower | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		5	4
Retail loans | Home equity | Consumer borrower | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		1	5
Retail loans | Home equity | Consumer borrower | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	0
Retail loans | Other consumer | Consumer borrower
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		1	5
Nonaccrual loans		0	0
Current loans		587	724
Total loans		588	729
Retail loans | Other consumer | Consumer borrower | 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		1	2
Retail loans | Other consumer | Consumer borrower | 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		0	3
Retail loans | Other consumer | Consumer borrower | 90 days or more past due and still accruing
Financing Receivable, Past Due [Line Items]
Loans past due and still accruing		$ 0	$ 0

[1] Primarily loans to real estate developers.

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