Loans and Leases - Accruing And Non-Accruing Loans By Class (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current, accruing	$ 61,119	$ 60,724
Total Accruing	61,248	60,830
Current, non-accruing	232	228
Total Non- Accruing	505	462
Loans and leases	61,753	61,292
30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due, accruing	119	85
Past due, non-accruing	75	30
90+ Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due, accruing	10	21
Past due, non-accruing	198	204
Commercial: | Commercial, financial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current, accruing	32,649	32,416
Total Accruing	32,705	32,449
Current, non-accruing	106	113
Total Non- Accruing	206	184
Loans and leases	32,911	32,633
Commercial: | Commercial, financial and industrial | 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due, accruing	55	32
Past due, non-accruing	30	18
Commercial: | Commercial, financial and industrial | 90+ Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due, accruing	1	1
Past due, non-accruing	70	53
Commercial: | Commercial, financial and industrial | General C I
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current, accruing	30,287	30,398
Total Accruing	30,343	30,430
Current, non-accruing	102	108
Total Non- Accruing	202	179
Loans and leases	30,545	30,609
Nonaccrual, no allowance	191	178
Commercial: | Commercial, financial and industrial | General C I | 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due, accruing	55	31
Past due, non-accruing	30	18
Commercial: | Commercial, financial and industrial | General C I | 90+ Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due, accruing	1	1
Past due, non-accruing	70	53
Commercial: | Commercial, financial and industrial | Loans to mortgage companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current, accruing	2,362	2,018
Total Accruing	2,362	2,019
Current, non-accruing	4	5
Total Non- Accruing	4	5
Loans and leases	2,366	2,024
Commercial: | Commercial, financial and industrial | Loans to mortgage companies | 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due, accruing	0	1
Past due, non-accruing	0	0
Commercial: | Commercial, financial and industrial | Loans to mortgage companies | 90+ Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due, accruing	0	0
Past due, non-accruing	0	0
Commercial: | Commercial, financial and industrial | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual, no allowance	150	129
Commercial: | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	14,426	14,216
Commercial: | Commercial real estate | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	14,426	14,216
Commercial: | Credit Card and Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	181	180
Commercial real estate | Commercial real estate | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current, accruing	14,261	14,072
Total Accruing	14,269	14,080
Current, non-accruing	57	41
Total Non- Accruing	157	136
Loans and leases	14,426	14,216
Commercial real estate | Commercial real estate | Commercial Real Estate | 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due, accruing	8	8
Past due, non-accruing	28	0
Commercial real estate | Commercial real estate | Commercial Real Estate | 90+ Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due, accruing	0	0
Past due, non-accruing	72	95
Consumer:
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	13,645	13,650
Consumer: | Consumer Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current, accruing	13,448	13,453
Total Accruing	13,505	13,510
Current, non-accruing	68	73
Total Non- Accruing	140	140
Loans and leases	13,645	13,650
Consumer: | Consumer Real Estate | 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due, accruing	51	40
Past due, non-accruing	17	12
Consumer: | Consumer Real Estate | 90+ Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due, accruing	6	17
Past due, non-accruing	55	55
Consumer: | Consumer Real Estate | Home Equity Line of Credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current, accruing	2,089	2,158
Total Accruing	2,104	2,173
Current, non-accruing	27	30
Total Non- Accruing	41	46
Loans and leases	2,145	2,219
Nonaccrual, no allowance	4	4
Consumer: | Consumer Real Estate | Home Equity Line of Credit | 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due, accruing	12	11
Past due, non-accruing	4	6
Consumer: | Consumer Real Estate | Home Equity Line of Credit | 90+ Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due, accruing	3	4
Past due, non-accruing	10	10
Consumer: | Consumer Real Estate | R E Installment Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current, accruing	11,359	11,295
Total Accruing	11,401	11,337
Current, non-accruing	41	43
Total Non- Accruing	99	94
Loans and leases	11,500	11,431
Nonaccrual, no allowance	9	10
Consumer: | Consumer Real Estate | R E Installment Loans | 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due, accruing	39	29
Past due, non-accruing	13	6
Consumer: | Consumer Real Estate | R E Installment Loans | 90+ Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due, accruing	3	13
Past due, non-accruing	45	45
Consumer: | Credit Card and Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current, accruing	761	783
Total Accruing	769	791
Current, non-accruing	1	1
Total Non- Accruing	2	2
Loans and leases	771	793
Consumer: | Credit Card and Other | 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due, accruing	5	5
Past due, non-accruing	0	0
Consumer: | Credit Card and Other | 90+ Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due, accruing	3	3
Past due, non-accruing	1	1
Consumer: | Credit Card and Other | Credit card
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current, accruing	267	271
Total Accruing	272	277
Current, non-accruing	0	0
Total Non- Accruing	0	0
Loans and leases	272	277
Consumer: | Credit Card and Other | Credit card | 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due, accruing	2	3
Past due, non-accruing	0	0
Consumer: | Credit Card and Other | Credit card | 90+ Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due, accruing	3	3
Past due, non-accruing	0	0
Consumer: | Credit Card and Other | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current, accruing	494	512
Total Accruing	497	514
Current, non-accruing	1	1
Total Non- Accruing	2	2
Loans and leases	499	516
Consumer: | Credit Card and Other | Other | 30-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due, accruing	3	2
Past due, non-accruing	0	0
Consumer: | Credit Card and Other | Other | 90+ Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due, accruing	0	0
Past due, non-accruing	$ 1	$ 1