v3.19.3.a.u2
Allowance For Credit Losses (Credit Quality Indicators) (Details) - USD ($)
$ in Millions
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income $ 82,963 $ 83,152 $ 79,947
Commercial And Industrial [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 39,971 39,282  
Commercial Real Estate Mortgage - Owner-Occupied [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 5,537 5,549  
Commercial Real Estate Construction - Owner-Occupied [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 331 384  
Commercial Investor Real Estate Mortgage [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 4,936 4,650  
Commercial Investor Real Estate Construction [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 1,621 1,786  
Residential First Mortgage [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 14,485 14,276  
Home Equity [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 8,384 9,257  
Indirect-vehicles [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 1,812 3,053  
Indirect-other consumer [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 3,249 2,349  
Consumer Credit Card Financing Receivable [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 1,387 1,345  
Other Consumer [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 1,250 1,221  
Pass [Member] | Commercial And Industrial [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 38,318 37,963  
Pass [Member] | Commercial Real Estate Mortgage - Owner-Occupied [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 5,183 5,193  
Pass [Member] | Commercial Real Estate Construction - Owner-Occupied [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 304 356  
Pass [Member] | Commercial Investor Real Estate Mortgage [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 4,738 4,444  
Pass [Member] | Commercial Investor Real Estate Construction [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 1,602 1,773  
Special Mention [Member] | Commercial And Industrial [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 598 666  
Special Mention [Member] | Commercial Real Estate Mortgage - Owner-Occupied [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 110 208  
Special Mention [Member] | Commercial Real Estate Construction - Owner-Occupied [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 5 7  
Special Mention [Member] | Commercial Investor Real Estate Mortgage [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 171 52  
Special Mention [Member] | Commercial Investor Real Estate Construction [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 5 6  
Substandard [Member] | Commercial And Industrial [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 708 346  
Substandard [Member] | Commercial Real Estate Mortgage - Owner-Occupied [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 171 81  
Substandard [Member] | Commercial Real Estate Construction - Owner-Occupied [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 11 13  
Substandard [Member] | Commercial Investor Real Estate Mortgage [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 25 143  
Substandard [Member] | Commercial Investor Real Estate Construction [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 14 7  
Accrual [Member] | Residential First Mortgage [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 14,458 14,236  
Accrual [Member] | Home Equity [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 8,337 9,194  
Accrual [Member] | Indirect-vehicles [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 1,812 3,053  
Accrual [Member] | Indirect-other consumer [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 3,249 2,349  
Accrual [Member] | Consumer Credit Card Financing Receivable [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 1,387 1,345  
Accrual [Member] | Other Consumer [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 1,250 1,221  
Non-Accrual [Member] | Commercial And Industrial [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 347 307  
Non-Accrual [Member] | Commercial Real Estate Mortgage - Owner-Occupied [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 73 67  
Non-Accrual [Member] | Commercial Real Estate Construction - Owner-Occupied [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 11 8  
Non-Accrual [Member] | Commercial Investor Real Estate Mortgage [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 2 11  
Non-Accrual [Member] | Commercial Investor Real Estate Construction [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 0 0  
Non-Accrual [Member] | Residential First Mortgage [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 27 40  
Non-Accrual [Member] | Home Equity [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 47 63  
Non-Accrual [Member] | Indirect-vehicles [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 0 0  
Non-Accrual [Member] | Indirect-other consumer [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 0 0  
Non-Accrual [Member] | Consumer Credit Card Financing Receivable [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 0 0  
Non-Accrual [Member] | Other Consumer [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 0 0  
Commercial Portfolio Segment [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 45,839 45,215 42,640
Commercial Portfolio Segment [Member] | Pass [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 43,805 43,512  
Commercial Portfolio Segment [Member] | Special Mention [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 713 881  
Commercial Portfolio Segment [Member] | Substandard [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 890 440  
Commercial Portfolio Segment [Member] | Non-Accrual [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 431 382  
Total Investor Real Estate [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 6,557 6,436 5,834
Total Investor Real Estate [Member] | Pass [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 6,340 6,217  
Total Investor Real Estate [Member] | Special Mention [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 176 58  
Total Investor Real Estate [Member] | Substandard [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 39 150  
Total Investor Real Estate [Member] | Non-Accrual [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 2 11  
Consumer Portfolio Segment [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 30,567 31,501 $ 31,473
Consumer Portfolio Segment [Member] | Accrual [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income 30,493 31,398  
Consumer Portfolio Segment [Member] | Non-Accrual [Member]      
Financing Receivable, Recorded Investment [Line Items]      
Loans, net of unearned income $ 74 $ 103