Loans and Related Allowance for Credit Losses, Troubled Debt Restructurings Modifications by Type (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	$ 845	$ 951
Financial effects of modifications [Abstract]
Charge-offs	$ 10	$ 14
Weighted average interest rate reduction	10.15%	12.82%
Accounts, Notes, Loans and Financing Receivable Textual [Abstract]
Financing receivable, troubled debt restructuring	$ 9,700		$ 10,200
Loans and leases receivable, impaired, commitment to lend	471		$ 431
Total Commercial [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	111	$ 339
Financial effects of modifications [Abstract]
Charge-offs	$ 0	$ 6
Weighted average interest rate reduction	6.37%	0.92%
Commercial and industrial loans [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	$ 79	$ 231
Financial effects of modifications [Abstract]
Charge-offs	$ 0	$ 6
Weighted average interest rate reduction	9.94%	0.89%
Real estate mortgage [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	$ 32	$ 104
Financial effects of modifications [Abstract]
Charge-offs	$ 0	$ 0
Weighted average interest rate reduction	1.45%	0.93%
Real estate construction [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	$ 0	$ 1
Financial effects of modifications [Abstract]
Charge-offs	$ 0	$ 0
Weighted average interest rate reduction	0.00%	0.00%
Lease financing [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	$ 0	$ 3
Financial effects of modifications [Abstract]
Charge-offs	$ 0	$ 0
Weighted average interest rate reduction	0.00%	0.00%
Total Consumer [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	$ 734	$ 612
Loan restructuring, trial modifications, amount	211	0
Financial effects of modifications [Abstract]
Charge-offs	$ 10	$ 8
Weighted average interest rate reduction	10.43%	14.01%
Residential mortgage - first lien [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	$ 376	$ 539
Financial effects of modifications [Abstract]
Charge-offs	$ 1	$ 0
Weighted average interest rate reduction	1.58%	1.87%
Residential mortgage - junior lien [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	$ 29	$ 18
Financial effects of modifications [Abstract]
Charge-offs	$ 0	$ 1
Weighted average interest rate reduction	2.34%	2.41%
Credit card [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	$ 70	$ 32
Financial effects of modifications [Abstract]
Charge-offs	$ 0	$ 0
Weighted average interest rate reduction	19.12%	18.87%
Auto [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	$ 44	$ 15
Financial effects of modifications [Abstract]
Charge-offs	$ 9	$ 7
Weighted average interest rate reduction	4.91%	3.87%
Other consumer [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	$ 4	$ 8
Financial effects of modifications [Abstract]
Charge-offs	$ 0	$ 0
Weighted average interest rate reduction	11.64%	12.20%
Primary modification type, Principal forgiveness [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	$ 2	$ 0
Primary modification type, Principal forgiveness [Member] | Total Commercial [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	0	0
Primary modification type, Principal forgiveness [Member] | Commercial and industrial loans [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	0	0
Primary modification type, Principal forgiveness [Member] | Real estate mortgage [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	0	0
Primary modification type, Principal forgiveness [Member] | Real estate construction [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	0	0
Primary modification type, Principal forgiveness [Member] | Lease financing [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	0	0
Primary modification type, Principal forgiveness [Member] | Total Consumer [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	2	0
Loan restructuring, trial modifications, amount	0	0
Primary modification type, Principal forgiveness [Member] | Residential mortgage - first lien [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	1	0
Primary modification type, Principal forgiveness [Member] | Residential mortgage - junior lien [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	0	0
Primary modification type, Principal forgiveness [Member] | Credit card [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	0	0
Primary modification type, Principal forgiveness [Member] | Auto [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	1	0
Primary modification type, Principal forgiveness [Member] | Other consumer [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	0	0
Primary modification type, Interest rate reduction [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	155	57
Primary modification type, Interest rate reduction [Member] | Total Commercial [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	11	5
Primary modification type, Interest rate reduction [Member] | Commercial and industrial loans [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	6	1
Primary modification type, Interest rate reduction [Member] | Real estate mortgage [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	5	4
Primary modification type, Interest rate reduction [Member] | Real estate construction [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	0	0
Primary modification type, Interest rate reduction [Member] | Lease financing [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	0	0
Primary modification type, Interest rate reduction [Member] | Total Consumer [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	144	52
Loan restructuring, trial modifications, amount	0	0
Primary modification type, Interest rate reduction [Member] | Residential mortgage - first lien [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	60	7
Primary modification type, Interest rate reduction [Member] | Residential mortgage - junior lien [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	8	5
Primary modification type, Interest rate reduction [Member] | Credit card [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	70	32
Primary modification type, Interest rate reduction [Member] | Auto [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	3	1
Primary modification type, Interest rate reduction [Member] | Other consumer [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	3	7
Primary modification type, Other concessions [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	688	894
Primary modification type, Other concessions [Member] | Total Commercial [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	100	334
Primary modification type, Other concessions [Member] | Commercial and industrial loans [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	73	230
Primary modification type, Other concessions [Member] | Real estate mortgage [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	27	100
Primary modification type, Other concessions [Member] | Real estate construction [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	0	1
Primary modification type, Other concessions [Member] | Lease financing [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	0	3
Primary modification type, Other concessions [Member] | Total Consumer [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	588	560
Loan restructuring, trial modifications, amount	211	0
Primary modification type, Other concessions [Member] | Residential mortgage - first lien [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	315	532
Primary modification type, Other concessions [Member] | Residential mortgage - junior lien [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	21	13
Primary modification type, Other concessions [Member] | Credit card [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	0	0
Primary modification type, Other concessions [Member] | Auto [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	40	14
Primary modification type, Other concessions [Member] | Other consumer [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	1	1
Trial modifications [Member] | Total Consumer [Member]
Financial effects of modifications [Abstract]
Charge-offs	$ 0	$ 0
Weighted average interest rate reduction	0.00%	0.00%
Financial effects of modification, Recorded investment related to interest rate reduction [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	$ 155	$ 57
Financial effects of modification, Recorded investment related to interest rate reduction [Member] | Total Commercial [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	11	5
Financial effects of modification, Recorded investment related to interest rate reduction [Member] | Commercial and industrial loans [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	6	1
Financial effects of modification, Recorded investment related to interest rate reduction [Member] | Real estate mortgage [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	5	4
Financial effects of modification, Recorded investment related to interest rate reduction [Member] | Real estate construction [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	0	0
Financial effects of modification, Recorded investment related to interest rate reduction [Member] | Lease financing [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	0	0
Financial effects of modification, Recorded investment related to interest rate reduction [Member] | Total Consumer [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	144	52
Loan restructuring, trial modifications, amount	0	0
Financial effects of modification, Recorded investment related to interest rate reduction [Member] | Residential mortgage - first lien [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	60	7
Financial effects of modification, Recorded investment related to interest rate reduction [Member] | Residential mortgage - junior lien [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	8	5
Financial effects of modification, Recorded investment related to interest rate reduction [Member] | Credit card [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	70	32
Financial effects of modification, Recorded investment related to interest rate reduction [Member] | Auto [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	3	1
Financial effects of modification, Recorded investment related to interest rate reduction [Member] | Other consumer [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	3	7
Loans remodified [Member]
Primary Modification Type [Abstract]
Financing receivable, troubled debt restructuring, post modification	$ 118	$ 256