Credit Quality And Allowance For Credit Losses (Loans By Credit Quality Indicator and Vintage Year) (Details) - USD ($) $ in Millions		Jun. 30, 2021		Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		$ 50,228		$ 52,291
Financing Receivable, Originated in Current Fiscal Year		5,132		9,714
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		7,746		5,957
Financing Receivable, Originated Two Years before Latest Fiscal Year		5,430		4,523
Financing Receivable, Originated Three Years before Latest Fiscal Year		3,886		3,243
Financing Receivable, Originated Four Years before Latest Fiscal Year		2,623		1,913
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		5,090		4,282
Financing Receivable, Revolving		20,246		22,570
Financing Receivable, Revolving, Converted to Term Loan		75		89
Business loans | Commercial borrower
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		46,338		48,267
Financing Receivable, Originated in Current Fiscal Year		4,857		8,955
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		7,028		5,702
Financing Receivable, Originated Two Years before Latest Fiscal Year		5,213		4,388
Financing Receivable, Originated Three Years before Latest Fiscal Year		3,777		3,038
Financing Receivable, Originated Four Years before Latest Fiscal Year		2,484		1,712
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		4,526		3,795
Financing Receivable, Revolving		18,437		20,658
Financing Receivable, Revolving, Converted to Term Loan		16		19
Business loans | Commercial borrower | Domestic loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		30,207		32,753
Financing Receivable, Originated in Current Fiscal Year		3,374		6,021
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		3,900		2,597
Financing Receivable, Originated Two Years before Latest Fiscal Year		2,081		1,754
Financing Receivable, Originated Three Years before Latest Fiscal Year		1,414		1,167
Financing Receivable, Originated Four Years before Latest Fiscal Year		887		493
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		1,129		921
Financing Receivable, Revolving		17,406		19,781
Financing Receivable, Revolving, Converted to Term Loan		16		19
Business loans | Commercial borrower | Domestic loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	28,680		30,538
Financing Receivable, Originated in Current Fiscal Year	[1],[2]	3,319		5,991
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[1]	3,819	[2]	2,316
Financing Receivable, Originated Two Years before Latest Fiscal Year	[1]	1,876		1,563
Financing Receivable, Originated Three Years before Latest Fiscal Year	[1]	1,278		1,051
Financing Receivable, Originated Four Years before Latest Fiscal Year	[1]	823		429
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[1]	969		755
Financing Receivable, Revolving	[1]	16,582		18,416
Financing Receivable, Revolving, Converted to Term Loan	[1]	14		17
Business loans | Commercial borrower | Domestic loans | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	1,527		2,215
Financing Receivable, Originated in Current Fiscal Year	[3]	55		30
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[3]	81		281
Financing Receivable, Originated Two Years before Latest Fiscal Year	[3]	205		191
Financing Receivable, Originated Three Years before Latest Fiscal Year	[3]	136		116
Financing Receivable, Originated Four Years before Latest Fiscal Year	[3]	64		64
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[3]	160		166
Financing Receivable, Revolving	[3]	824		1,365
Financing Receivable, Revolving, Converted to Term Loan	[3]	2		2
Business loans | Commercial borrower | International loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		1,036		926
Financing Receivable, Originated in Current Fiscal Year		219		287
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		159		169
Financing Receivable, Originated Two Years before Latest Fiscal Year		146		121
Financing Receivable, Originated Three Years before Latest Fiscal Year		49		15
Financing Receivable, Originated Four Years before Latest Fiscal Year		10		10
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		63		66
Financing Receivable, Revolving		390		258
Financing Receivable, Revolving, Converted to Term Loan		0		0
Business loans | Commercial borrower | International loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	980		861
Financing Receivable, Originated in Current Fiscal Year	[1]	199		274
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[1]	145		161
Financing Receivable, Originated Two Years before Latest Fiscal Year	[1]	143		103
Financing Receivable, Originated Three Years before Latest Fiscal Year	[1]	48		11
Financing Receivable, Originated Four Years before Latest Fiscal Year	[1]	6		3
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[1]	54		64
Financing Receivable, Revolving	[1]	385		245
Financing Receivable, Revolving, Converted to Term Loan	[1]	0		0
Business loans | Commercial borrower | International loans | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	56		65
Financing Receivable, Originated in Current Fiscal Year	[3]	20		13
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[3]	14		8
Financing Receivable, Originated Two Years before Latest Fiscal Year	[3]	3		18
Financing Receivable, Originated Three Years before Latest Fiscal Year	[3]	1		4
Financing Receivable, Originated Four Years before Latest Fiscal Year	[3]	4		7
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[3]	9		2
Financing Receivable, Revolving	[3]	5		13
Financing Receivable, Revolving, Converted to Term Loan	[3]	0		0
Business loans | Commercial borrower | Real estate construction | Domestic loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		3,172		4,082
Financing Receivable, Originated in Current Fiscal Year		142		436
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		731		1,108
Financing Receivable, Originated Two Years before Latest Fiscal Year		1,182		1,249
Financing Receivable, Originated Three Years before Latest Fiscal Year		574		639
Financing Receivable, Originated Four Years before Latest Fiscal Year		302		335
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		89		142
Financing Receivable, Revolving		152		173
Financing Receivable, Revolving, Converted to Term Loan		0		0
Business loans | Commercial borrower | Real estate construction | Domestic loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	3,102		4,035
Financing Receivable, Originated in Current Fiscal Year	[1]	142		433
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[1]	728		1,080
Financing Receivable, Originated Two Years before Latest Fiscal Year	[1]	1,152		1,244
Financing Receivable, Originated Three Years before Latest Fiscal Year	[1]	557		631
Financing Receivable, Originated Four Years before Latest Fiscal Year	[1]	294		335
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[1]	80		141
Financing Receivable, Revolving	[1]	149		171
Financing Receivable, Revolving, Converted to Term Loan	[1]	0		0
Business loans | Commercial borrower | Real estate construction | Domestic loans | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	70		47
Financing Receivable, Originated in Current Fiscal Year	[3]	0		3
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[3]	3		28
Financing Receivable, Originated Two Years before Latest Fiscal Year	[3]	30		5
Financing Receivable, Originated Three Years before Latest Fiscal Year	[3]	17		8
Financing Receivable, Originated Four Years before Latest Fiscal Year	[3]	8		0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[3]	9		1
Financing Receivable, Revolving	[3]	3		2
Financing Receivable, Revolving, Converted to Term Loan	[3]	0		0
Business loans | Commercial borrower | Commercial mortgage | Domestic loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		11,334		9,912
Financing Receivable, Originated in Current Fiscal Year		1,067		2,100
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		2,136		1,689
Financing Receivable, Originated Two Years before Latest Fiscal Year		1,674		1,188
Financing Receivable, Originated Three Years before Latest Fiscal Year		1,672		1,165
Financing Receivable, Originated Four Years before Latest Fiscal Year		1,238		859
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		3,058		2,465
Financing Receivable, Revolving		489		446
Financing Receivable, Revolving, Converted to Term Loan		0		0
Business loans | Commercial borrower | Commercial mortgage | Domestic loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	10,927		9,399
Financing Receivable, Originated in Current Fiscal Year	[1]	1,064		2,053
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[1]	2,088		1,559
Financing Receivable, Originated Two Years before Latest Fiscal Year	[1]	1,611		1,146
Financing Receivable, Originated Three Years before Latest Fiscal Year	[1]	1,636		1,120
Financing Receivable, Originated Four Years before Latest Fiscal Year	[1]	1,206		818
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[1]	2,848		2,272
Financing Receivable, Revolving	[1]	474		431
Financing Receivable, Revolving, Converted to Term Loan	[1]	0		0
Business loans | Commercial borrower | Commercial mortgage | Domestic loans | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	407		513
Financing Receivable, Originated in Current Fiscal Year	[3]	3		47
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[3]	48		130
Financing Receivable, Originated Two Years before Latest Fiscal Year	[3]	63		42
Financing Receivable, Originated Three Years before Latest Fiscal Year	[3]	36		45
Financing Receivable, Originated Four Years before Latest Fiscal Year	[3]	32		41
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[3]	210		193
Financing Receivable, Revolving	[3]	15		15
Financing Receivable, Revolving, Converted to Term Loan	[3]	0		0
Business loans | Commercial borrower | Lease financing | Domestic loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		589		594
Financing Receivable, Originated in Current Fiscal Year		55		111
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		102		139
Financing Receivable, Originated Two Years before Latest Fiscal Year		130		76
Financing Receivable, Originated Three Years before Latest Fiscal Year		68		52
Financing Receivable, Originated Four Years before Latest Fiscal Year		47		15
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		187		201
Financing Receivable, Revolving		0		0
Financing Receivable, Revolving, Converted to Term Loan		0		0
Business loans | Commercial borrower | Lease financing | Domestic loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	553		567
Financing Receivable, Originated in Current Fiscal Year	[1]	55		109
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[1]	100		122
Financing Receivable, Originated Two Years before Latest Fiscal Year	[1]	108		71
Financing Receivable, Originated Three Years before Latest Fiscal Year	[1]	58		50
Financing Receivable, Originated Four Years before Latest Fiscal Year	[1]	46		14
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[1]	186		201
Financing Receivable, Revolving	[1]	0		0
Financing Receivable, Revolving, Converted to Term Loan	[1]	0		0
Business loans | Commercial borrower | Lease financing | Domestic loans | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	36		27
Financing Receivable, Originated in Current Fiscal Year	[3]	0		2
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[3]	2		17
Financing Receivable, Originated Two Years before Latest Fiscal Year	[3]	22		5
Financing Receivable, Originated Three Years before Latest Fiscal Year	[3]	10		2
Financing Receivable, Originated Four Years before Latest Fiscal Year	[3]	1		1
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[3]	1		0
Financing Receivable, Revolving	[3]	0		0
Financing Receivable, Revolving, Converted to Term Loan	[3]	0		0
Retail loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		3,890		4,024
Financing Receivable, Originated in Current Fiscal Year		275		759
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		718		255
Financing Receivable, Originated Two Years before Latest Fiscal Year		217		135
Financing Receivable, Originated Three Years before Latest Fiscal Year		109		205
Financing Receivable, Originated Four Years before Latest Fiscal Year		139		201
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		564		487
Financing Receivable, Revolving		1,809		1,912
Financing Receivable, Revolving, Converted to Term Loan		59		70
Retail loans | Residential mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		1,807		1,830
Financing Receivable, Originated in Current Fiscal Year		225		646
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		637		232
Financing Receivable, Originated Two Years before Latest Fiscal Year		199		121
Financing Receivable, Originated Three Years before Latest Fiscal Year		99		203
Financing Receivable, Originated Four Years before Latest Fiscal Year		138		198
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		509		430
Financing Receivable, Revolving		0		0
Financing Receivable, Revolving, Converted to Term Loan		0		0
Retail loans | Residential mortgage | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	1,760		1,779
Financing Receivable, Originated in Current Fiscal Year	[1]	219		639
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[1]	636		230
Financing Receivable, Originated Two Years before Latest Fiscal Year	[1]	197		119
Financing Receivable, Originated Three Years before Latest Fiscal Year	[1]	96		197
Financing Receivable, Originated Four Years before Latest Fiscal Year	[1]	131		196
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[1]	481		398
Financing Receivable, Revolving	[1]	0		0
Financing Receivable, Revolving, Converted to Term Loan	[1]	0		0
Retail loans | Residential mortgage | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	47		51
Financing Receivable, Originated in Current Fiscal Year	[3]	6		7
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[3]	1		2
Financing Receivable, Originated Two Years before Latest Fiscal Year	[3]	2		2
Financing Receivable, Originated Three Years before Latest Fiscal Year	[3]	3		6
Financing Receivable, Originated Four Years before Latest Fiscal Year	[3]	7		2
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[3]	28		32
Financing Receivable, Revolving	[3]	0		0
Financing Receivable, Revolving, Converted to Term Loan	[3]	0		0
Retail loans | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		2,083		2,194
Financing Receivable, Originated in Current Fiscal Year		50		113
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		81		23
Financing Receivable, Originated Two Years before Latest Fiscal Year		18		14
Financing Receivable, Originated Three Years before Latest Fiscal Year		10		2
Financing Receivable, Originated Four Years before Latest Fiscal Year		1		3
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		55		57
Financing Receivable, Revolving		1,809		1,912
Financing Receivable, Revolving, Converted to Term Loan		59		70
Retail loans | Home equity | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		1,548		1,588
Financing Receivable, Originated in Current Fiscal Year		0		0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		0		0
Financing Receivable, Originated Two Years before Latest Fiscal Year		0		0
Financing Receivable, Originated Three Years before Latest Fiscal Year		0		0
Financing Receivable, Originated Four Years before Latest Fiscal Year		0		0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		14		16
Financing Receivable, Revolving		1,475		1,502
Financing Receivable, Revolving, Converted to Term Loan		59		70
Retail loans | Home equity | Home equity | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	1,531		1,567
Financing Receivable, Originated in Current Fiscal Year	[1]	0		0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[1]	0		0
Financing Receivable, Originated Two Years before Latest Fiscal Year	[1]	0		0
Financing Receivable, Originated Three Years before Latest Fiscal Year	[1]	0		0
Financing Receivable, Originated Four Years before Latest Fiscal Year	[1]	0		0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[1]	14		15
Financing Receivable, Revolving	[1]	1,464		1,489
Financing Receivable, Revolving, Converted to Term Loan	[1]	53		63
Retail loans | Home equity | Home equity | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	17		21
Financing Receivable, Originated in Current Fiscal Year	[3]	0		0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[3]	0		0
Financing Receivable, Originated Two Years before Latest Fiscal Year	[3]	0		0
Financing Receivable, Originated Three Years before Latest Fiscal Year	[3]	0		0
Financing Receivable, Originated Four Years before Latest Fiscal Year	[3]	0		0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[3]	0		1
Financing Receivable, Revolving	[3]	11		13
Financing Receivable, Revolving, Converted to Term Loan	[3]	6		7
Retail loans | Home equity | Other consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans		535		606
Financing Receivable, Originated in Current Fiscal Year		50		113
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year		81		23
Financing Receivable, Originated Two Years before Latest Fiscal Year		18		14
Financing Receivable, Originated Three Years before Latest Fiscal Year		10		2
Financing Receivable, Originated Four Years before Latest Fiscal Year		1		3
Financing Receivable, Originated Five or More Years before Latest Fiscal Year		41		41
Financing Receivable, Revolving		334		410
Financing Receivable, Revolving, Converted to Term Loan		0		0
Retail loans | Home equity | Other consumer | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[1]	519		598
Financing Receivable, Originated in Current Fiscal Year	[1]	50		113
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[1]	81		23
Financing Receivable, Originated Two Years before Latest Fiscal Year	[1]	18		12
Financing Receivable, Originated Three Years before Latest Fiscal Year	[1]	9		2
Financing Receivable, Originated Four Years before Latest Fiscal Year	[1]	1		3
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[1]	34		41
Financing Receivable, Revolving	[1]	326		404
Financing Receivable, Revolving, Converted to Term Loan	[1]	0		0
Retail loans | Home equity | Other consumer | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	[3]	16		8
Financing Receivable, Originated in Current Fiscal Year	[3]	0		0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	[3]	0		0
Financing Receivable, Originated Two Years before Latest Fiscal Year	[3]	0		2
Financing Receivable, Originated Three Years before Latest Fiscal Year	[3]	1		0
Financing Receivable, Originated Four Years before Latest Fiscal Year	[3]	0		0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	[3]	7		0
Financing Receivable, Revolving	[3]	8		6
Financing Receivable, Revolving, Converted to Term Loan	[3]	$ 0		$ 0

[1] Includes all loans not included in the categories of special mention, substandard or nonaccrual.

[2] Includes Small Business Administration Paycheck Protection Program (PPP) loans of $1.0 billion and $1.8 billion in 2021 and 2020, respectively, at June 30, 2021, and PPP loans of $3.5 billion in 2020 at December 31, 2020.

[3] Includes loans with an internal rating of special mention, substandard loans for which the accrual of interest has not been discontinued and nonaccrual loans. Special mention loans have potential credit weaknesses that deserve management’s close attention, such as loans to borrowers who may be experiencing financial difficulties that may result in deterioration of repayment prospects from the borrower at some future date. Accruing substandard loans have a well-defined weakness, or weaknesses, such as loans to borrowers who may be experiencing losses from operations or inadequate liquidity of a degree and duration that jeopardizes the orderly repayment of the loan. Substandard loans are also distinguished by the distinct possibility of loss in the future if these weaknesses are not corrected. Nonaccrual loans are loans for which the accrual of interest has been discontinued. For further information regarding nonaccrual loans, refer to the Nonperforming Assets subheading in Note 1 - Basis of Presentation and Accounting Policies on page F-59 in the Corporation's 2020 Annual Report. These categories are generally consistent with the "special mention" and "substandard" categories as defined by regulatory authorities. A minority of nonaccrual loans are consistent with the "doubtful" category.