Credit Quality And Allowance For Credit Losses (Loans By Credit Quality Indicator) (Details) - USD ($) $ in Millions		Sep. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Total loans		$ 49,010	$ 49,173
Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1]	47,340	46,942
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2]	760	768
Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3]	680	1,061
Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4]	230	402
Business loans | Commercial borrower
Financing Receivable, Recorded Investment [Line Items]
Total loans		44,627	44,631
Business loans | Commercial borrower | Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1]	43,027	42,464
Business loans | Commercial borrower | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2]	752	764
Business loans | Commercial borrower | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3]	671	1,053
Business loans | Commercial borrower | Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4]	177	350
Business loans | Commercial borrower | Domestic loans
Financing Receivable, Recorded Investment [Line Items]
Total loans		30,889	31,060
Business loans | Commercial borrower | Domestic loans | Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1]	29,628	29,263
Business loans | Commercial borrower | Domestic loans | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2]	580	591
Business loans | Commercial borrower | Domestic loans | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3]	532	897
Business loans | Commercial borrower | Domestic loans | Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4]	149	309
Business loans | Commercial borrower | International loans
Financing Receivable, Recorded Investment [Line Items]
Total loans		1,090	983
Business loans | Commercial borrower | International loans | Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1]	1,066	946
Business loans | Commercial borrower | International loans | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2]	3	11
Business loans | Commercial borrower | International loans | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3]	17	20
Business loans | Commercial borrower | International loans | Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4]	4	6
Business loans | Real estate construction | Commercial borrower | Domestic loans
Financing Receivable, Recorded Investment [Line Items]
Total loans		3,158	2,961
Business loans | Real estate construction | Commercial borrower | Domestic loans | Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1]	3,127	2,957
Business loans | Real estate construction | Commercial borrower | Domestic loans | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2]	31	4
Business loans | Real estate construction | Commercial borrower | Domestic loans | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3]	0	0
Business loans | Real estate construction | Commercial borrower | Domestic loans | Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4]	0	0
Business loans | Real estate construction | Commercial borrower | Domestic loans | Commercial Real Estate business line
Financing Receivable, Recorded Investment [Line Items]
Total loans	[5]	2,780	2,630
Business loans | Real estate construction | Commercial borrower | Domestic loans | Commercial Real Estate business line | Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1],[5]	2,757	2,630
Business loans | Real estate construction | Commercial borrower | Domestic loans | Commercial Real Estate business line | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2],[5]	23	0
Business loans | Real estate construction | Commercial borrower | Domestic loans | Commercial Real Estate business line | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3],[5]	0	0
Business loans | Real estate construction | Commercial borrower | Domestic loans | Commercial Real Estate business line | Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4],[5]	0	0
Business loans | Real estate construction | Commercial borrower | Domestic loans | Other business lines
Financing Receivable, Recorded Investment [Line Items]
Total loans	[6]	378	331
Business loans | Real estate construction | Commercial borrower | Domestic loans | Other business lines | Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1],[6]	370	327
Business loans | Real estate construction | Commercial borrower | Domestic loans | Other business lines | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2],[6]	8	4
Business loans | Real estate construction | Commercial borrower | Domestic loans | Other business lines | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3],[6]	0	0
Business loans | Real estate construction | Commercial borrower | Domestic loans | Other business lines | Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4],[6]	0	0
Business loans | Real estate mortgage | Commercial borrower | Domestic loans
Financing Receivable, Recorded Investment [Line Items]
Total loans		9,019	9,159
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1]	8,742	8,858
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2]	135	135
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3]	120	135
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4]	22	31
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Commercial Real Estate business line
Financing Receivable, Recorded Investment [Line Items]
Total loans	[5]	1,760	1,831
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Commercial Real Estate business line | Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1],[5]	1,698	1,759
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Commercial Real Estate business line | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2],[5]	15	20
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Commercial Real Estate business line | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3],[5]	45	43
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Commercial Real Estate business line | Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4],[5]	2	9
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Other business lines
Financing Receivable, Recorded Investment [Line Items]
Total loans	[6]	7,259	7,328
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Other business lines | Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1],[6]	7,044	7,099
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Other business lines | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2],[6]	120	115
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Other business lines | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3],[6]	75	92
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Other business lines | Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4],[6]	20	22
Business loans | Lease financing | Commercial borrower | Domestic loans
Financing Receivable, Recorded Investment [Line Items]
Total loans		471	468
Business loans | Lease financing | Commercial borrower | Domestic loans | Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1]	464	440
Business loans | Lease financing | Commercial borrower | Domestic loans | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2]	3	23
Business loans | Lease financing | Commercial borrower | Domestic loans | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3]	2	1
Business loans | Lease financing | Commercial borrower | Domestic loans | Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4]	2	4
Retail loans
Financing Receivable, Recorded Investment [Line Items]
Total loans		4,383	4,542
Retail loans | Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1]	4,313	4,478
Retail loans | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2]	8	4
Retail loans | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3]	9	8
Retail loans | Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4]	53	52
Retail loans | Consumer borrower
Financing Receivable, Recorded Investment [Line Items]
Total loans		2,436	2,554
Retail loans | Consumer borrower | Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1]	2,407	2,523
Retail loans | Consumer borrower | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2]	1	2
Retail loans | Consumer borrower | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3]	9	8
Retail loans | Consumer borrower | Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4]	19	21
Retail loans | Real estate mortgage
Financing Receivable, Recorded Investment [Line Items]
Total loans		1,947	1,988
Retail loans | Real estate mortgage | Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1]	1,906	1,955
Retail loans | Real estate mortgage | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2]	7	2
Retail loans | Real estate mortgage | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3]	0	0
Retail loans | Real estate mortgage | Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4]	34	31
Retail loans | Home equity | Consumer borrower
Financing Receivable, Recorded Investment [Line Items]
Total loans		1,726	1,816
Retail loans | Home equity | Consumer borrower | Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1]	1,698	1,786
Retail loans | Home equity | Consumer borrower | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2]	0	1
Retail loans | Home equity | Consumer borrower | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3]	9	8
Retail loans | Home equity | Consumer borrower | Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4]	19	21
Retail loans | Other consumer | Consumer borrower
Financing Receivable, Recorded Investment [Line Items]
Total loans		710	738
Retail loans | Other consumer | Consumer borrower | Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	[1]	709	737
Retail loans | Other consumer | Consumer borrower | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	[2]	1	1
Retail loans | Other consumer | Consumer borrower | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	[3]	0	0
Retail loans | Other consumer | Consumer borrower | Nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Total loans	[4]	$ 0	$ 0

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

[2] Special mention loans are accruing loans that 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. This category is generally consistent with the "special mention" category as defined by regulatory authorities.

[3] Substandard loans are accruing loans that 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 also are distinguished by the distinct possibility of loss in the future if these weaknesses are not corrected. This category is generally consistent with the "substandard" category as defined by regulatory authorities.

[4] 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 pages F-51 and F-52 in the Corporation's 2017 Annual Report. A significant majority of nonaccrual loans are generally consistent with the "substandard" category and the remainder are generally consistent with the "doubtful" category as defined by regulatory authorities.

[5] Primarily loans to real estate developers.

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