Credit Quality And Allowance For Credit Losses (Aging Analysis Of Loans) (Details) - USD ($) $ in Millions		Sep. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		$ 254	$ 337
Nonaccrual loans		230	402
Current loans		48,526	48,434
Total loans		49,010	49,173
30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		161	159
60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		65	143
90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		28	35
Business loans | Commercial borrower
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		226	314
Nonaccrual loans		177	350
Current loans		44,224	43,967
Total loans		44,627	44,631
Business loans | Commercial borrower | 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		142	140
Business loans | Commercial borrower | 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		56	140
Business loans | Commercial borrower | 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		28	34
Business loans | Commercial borrower | Domestic loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		149	225
Nonaccrual loans		149	309
Current loans		30,591	30,526
Total loans		30,889	31,060
Business loans | Commercial borrower | Domestic loans | 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		74	79
Business loans | Commercial borrower | Domestic loans | 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		50	134
Business loans | Commercial borrower | Domestic loans | 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		25	12
Business loans | Commercial borrower | International loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	13
Nonaccrual loans		4	6
Current loans		1,086	964
Total loans		1,090	983
Business loans | Commercial borrower | International loans | 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	13
Business loans | Commercial borrower | International loans | 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	0
Business loans | Commercial borrower | International loans | 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	0
Business loans | Real estate construction | Commercial borrower | Domestic loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		36	7
Nonaccrual loans		0	0
Current loans		3,122	2,954
Total loans		3,158	2,961
Business loans | Real estate construction | Commercial borrower | Domestic loans | 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		36	7
Business loans | Real estate construction | Commercial borrower | Domestic loans | 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	0
Business loans | Real estate construction | Commercial borrower | Domestic loans | 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, 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, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[1]	0	3
Nonaccrual loans	[1]	0	0
Current loans	[1]	2,780	2,627
Total loans	[1]	2,780	2,630
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, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[1]	0	3
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, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[1]	0	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, Recorded Investment, 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, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[2]	36	4
Nonaccrual loans	[2]	0	0
Current loans	[2]	342	327
Total loans	[2]	378	331
Business loans | Real estate construction | Commercial borrower | Domestic loans | Other business lines | 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[2]	36	4
Business loans | Real estate construction | Commercial borrower | Domestic loans | Other business lines | 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, 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 | 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[2]	0	0
Business loans | Real estate mortgage | Commercial borrower | Domestic loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		41	69
Nonaccrual loans		22	31
Current loans		8,956	9,059
Total loans		9,019	9,159
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		32	41
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		6	6
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		3	22
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Commercial Real Estate business line
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[1]	1	14
Nonaccrual loans	[1]	2	9
Current loans	[1]	1,757	1,808
Total loans	[1]	1,760	1,831
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Commercial Real Estate business line | 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[1]	1	14
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Commercial Real Estate business line | 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[1]	0	0
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Commercial Real Estate business line | 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[1]	0	0
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Other business lines
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[2]	40	55
Nonaccrual loans	[2]	20	22
Current loans	[2]	7,199	7,251
Total loans	[2]	7,259	7,328
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Other business lines | 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[2]	31	27
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Other business lines | 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[2]	6	6
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Other business lines | 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing	[2]	3	22
Business loans | Lease financing | Commercial borrower | Domestic loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	0
Nonaccrual loans		2	4
Current loans		469	464
Total loans		471	468
Business loans | Lease financing | Commercial borrower | Domestic loans | 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	0
Business loans | Lease financing | Commercial borrower | Domestic loans | 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, 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, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	0
Retail loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		28	23
Nonaccrual loans		53	52
Current loans		4,302	4,467
Total loans		4,383	4,542
Retail loans | 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		19	19
Retail loans | 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		9	3
Retail loans | 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	1
Retail loans | Consumer borrower
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		10	11
Nonaccrual loans		19	21
Current loans		2,407	2,522
Total loans		2,436	2,554
Retail loans | Consumer borrower | 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		8	9
Retail loans | Consumer borrower | 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		2	1
Retail loans | Consumer borrower | 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	1
Retail loans | Real estate mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		18	12
Nonaccrual loans		34	31
Current loans		1,895	1,945
Total loans		1,947	1,988
Retail loans | Real estate mortgage | 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		11	10
Retail loans | Real estate mortgage | 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		7	2
Retail loans | Real estate mortgage | 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	0
Retail loans | Home equity | Consumer borrower
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		8	6
Nonaccrual loans		19	21
Current loans		1,699	1,789
Total loans		1,726	1,816
Retail loans | Home equity | Consumer borrower | 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		6	5
Retail loans | Home equity | Consumer borrower | 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		2	1
Retail loans | Home equity | Consumer borrower | 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	0
Retail loans | Other consumer | Consumer borrower
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		2	5
Nonaccrual loans		0	0
Current loans		708	733
Total loans		710	738
Retail loans | Other consumer | Consumer borrower | 30 to 59 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		2	4
Retail loans | Other consumer | Consumer borrower | 60 to 89 days past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		0	0
Retail loans | Other consumer | Consumer borrower | 90 days or more past due and still accruing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans past due and still accruing		$ 0	$ 1

[1] Primarily loans to real estate developers.

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