Credit Quality And Allowance For Credit Losses (Loans By Credit Quality Indicator) (Details) - USD ($)
$ in Millions
Mar. 31, 2018
Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]    
Total loans $ 49,240 $ 49,173
Pass    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [1] 47,120 46,942
Special Mention    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [2] 717 768
Substandard    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [3] 1,077 1,061
Nonaccrual    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [4] 326 402
Business loans | Commercial borrower    
Financing Receivable, Recorded Investment [Line Items]    
Total loans 44,723 44,631
Business loans | Commercial borrower | Pass    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [1] 42,664 42,464
Business loans | Commercial borrower | Special Mention    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [2] 715 764
Business loans | Commercial borrower | Substandard    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [3] 1,066 1,053
Business loans | Commercial borrower | Nonaccrual    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [4] 278 350
Business loans | Commercial borrower | Domestic loans    
Financing Receivable, Recorded Investment [Line Items]    
Total loans 30,909 31,060
Business loans | Commercial borrower | Domestic loans | Pass    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [1] 29,195 29,263
Business loans | Commercial borrower | Domestic loans | Special Mention    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [2] 579 591
Business loans | Commercial borrower | Domestic loans | Substandard    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [3] 893 897
Business loans | Commercial borrower | Domestic loans | Nonaccrual    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [4] 242 309
Business loans | Commercial borrower | International loans    
Financing Receivable, Recorded Investment [Line Items]    
Total loans 964 983
Business loans | Commercial borrower | International loans | Pass    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [1] 926 946
Business loans | Commercial borrower | International loans | Special Mention    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [2] 5 11
Business loans | Commercial borrower | International loans | Substandard    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [3] 29 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 3,114 2,961
Business loans | Real estate construction | Commercial borrower | Domestic loans | Pass    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [1] 3,110 2,957
Business loans | Real estate construction | Commercial borrower | Domestic loans | Special Mention    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [2] 4 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],[6] 2,758 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] 2,758 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] 0 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 [7],[8] 356 331
Business loans | Real estate construction | Commercial borrower | Domestic loans | Other business lines | Pass    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [1],[7] 352 327
Business loans | Real estate construction | Commercial borrower | Domestic loans | Other business lines | Special Mention    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [2],[7] 4 4
Business loans | Real estate construction | Commercial borrower | Domestic loans | Other business lines | Substandard    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [3],[7] 0 0
Business loans | Real estate construction | Commercial borrower | Domestic loans | Other business lines | Nonaccrual    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [4],[7] 0 0
Business loans | Real estate mortgage | Commercial borrower | Domestic loans    
Financing Receivable, Recorded Investment [Line Items]    
Total loans 9,272 9,159
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Pass    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [1] 8,980 8,858
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Special Mention    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [2] 122 135
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Substandard    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [3] 141 135
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Nonaccrual    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [4] 29 31
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Commercial Real Estate business line    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [5],[6] 1,906 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] 1,836 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] 46 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] 9 9
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Other business lines    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [7],[8] 7,366 7,328
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Other business lines | Pass    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [1],[7] 7,144 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],[7] 107 115
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Other business lines | Substandard    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [3],[7] 95 92
Business loans | Real estate mortgage | Commercial borrower | Domestic loans | Other business lines | Nonaccrual    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [4],[7] 20 22
Business loans | Lease financing | Commercial borrower | Domestic loans    
Financing Receivable, Recorded Investment [Line Items]    
Total loans 464 468
Business loans | Lease financing | Commercial borrower | Domestic loans | Pass    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [1] 453 440
Business loans | Lease financing | Commercial borrower | Domestic loans | Special Mention    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [2] 5 23
Business loans | Lease financing | Commercial borrower | Domestic loans | Substandard    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [3] 3 1
Business loans | Lease financing | Commercial borrower | Domestic loans | Nonaccrual    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [4] 3 4
Retail loans    
Financing Receivable, Recorded Investment [Line Items]    
Total loans 4,517 4,542
Retail loans | Pass    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [1] 4,456 4,478
Retail loans | Special Mention    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [2] 2 4
Retail loans | Substandard    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [3] 11 8
Retail loans | Nonaccrual    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [4] 48 52
Retail loans | Consumer borrower    
Financing Receivable, Recorded Investment [Line Items]    
Total loans 2,514 2,554
Retail loans | Consumer borrower | Pass    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [1] 2,483 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] 11 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 2,003 1,988
Retail loans | Real estate mortgage | Pass    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [1] 1,973 1,955
Retail loans | Real estate mortgage | Special Mention    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [2] 1 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] 29 31
Retail loans | Home equity | Consumer borrower    
Financing Receivable, Recorded Investment [Line Items]    
Total loans 1,763 1,816
Retail loans | Home equity | Consumer borrower | Pass    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [1] 1,733 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] 11 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 751 738
Retail loans | Other consumer | Consumer borrower | Pass    
Financing Receivable, Recorded Investment [Line Items]    
Total loans [1] 750 737
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 to real estate developers.
[7] Primarily loans secured by owner-occupied real estate.
[8] Primarily loans secured by owner-occupied real estate.