CREDIT QUALITY AND THE ALLOWANCE FOR CREDIT LOSSES - Accruing and Non-accruing Past Due Amounts (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Financing Receivable, Past Due [Line Items]
Loans and leases	$ 139,203	$ 145,959
Loans and leases, nonaccrual	1,664	1,364
Loans and leases, nonaccrual with no related ACL	398	453
FHA, VA And USDA Loans
Financing Receivable, Past Due [Line Items]
Loans and leases	1,042	1,122
Loans and leases, nonaccrual	0	0
Loans and leases, nonaccrual with no related ACL	0	0
Financing Receivables, Current
Financing Receivable, Past Due [Line Items]
Loans and leases	136,320	143,111
Financing Receivables, Current | FHA, VA And USDA Loans
Financing Receivable, Past Due [Line Items]
Loans and leases	696	675
Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans and leases	769	818
Financing Receivables, 30 to 59 Days Past Due | FHA, VA And USDA Loans
Financing Receivable, Past Due [Line Items]
Loans and leases	119	128
Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans and leases	254	333
Financing Receivables, 60 to 89 Days Past Due | FHA, VA And USDA Loans
Financing Receivable, Past Due [Line Items]
Loans and leases	55	76
Financing Receivables, 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Loans and leases	196	333
Financing Receivables, 90 Days or More Past Due | FHA, VA And USDA Loans
Financing Receivable, Past Due [Line Items]
Loans and leases	172	243
Commercial
Financing Receivable, Past Due [Line Items]
Loans and leases	69,776	74,445
Loans and leases, nonaccrual	1,017	774
Loans and leases, nonaccrual with no related ACL	63	101
Commercial | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Loans and leases	42,551	44,974
Loans and leases, nonaccrual	241	297
Loans and leases, nonaccrual with no related ACL	31	30
Commercial | Commercial real estate
Financing Receivable, Past Due [Line Items]
Loans and leases	27,225	29,471
Loans and leases, nonaccrual	776	477
Loans and leases, nonaccrual with no related ACL	32	71
Commercial | Financing Receivables, Current
Financing Receivable, Past Due [Line Items]
Loans and leases	68,459	73,336
Commercial | Financing Receivables, Current | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Loans and leases	42,247	44,591
Commercial | Financing Receivables, Current | Commercial real estate
Financing Receivable, Past Due [Line Items]
Loans and leases	26,212	28,745
Commercial | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans and leases	239	212
Commercial | Financing Receivables, 30 to 59 Days Past Due | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Loans and leases	35	62
Commercial | Financing Receivables, 30 to 59 Days Past Due | Commercial real estate
Financing Receivable, Past Due [Line Items]
Loans and leases	204	150
Commercial | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans and leases	47	77
Commercial | Financing Receivables, 60 to 89 Days Past Due | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Loans and leases	20	18
Commercial | Financing Receivables, 60 to 89 Days Past Due | Commercial real estate
Financing Receivable, Past Due [Line Items]
Loans and leases	27	59
Commercial | Financing Receivables, 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Loans and leases	14	46
Commercial | Financing Receivables, 90 Days or More Past Due | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Loans and leases	8	6
Commercial | Financing Receivables, 90 Days or More Past Due | Commercial real estate
Financing Receivable, Past Due [Line Items]
Loans and leases	6	40
Retail
Financing Receivable, Past Due [Line Items]
Loans and leases	69,427	71,514
Loans and leases, nonaccrual	647	590
Loans and leases, nonaccrual with no related ACL	335	352
Retail | Residential mortgages
Financing Receivable, Past Due [Line Items]
Loans and leases	32,726	31,332
Loans and leases, nonaccrual	192	177
Loans and leases, nonaccrual with no related ACL	142	144
Retail | Home equity
Financing Receivable, Past Due [Line Items]
Loans and leases	16,495	15,040
Loans and leases, nonaccrual	283	285
Loans and leases, nonaccrual with no related ACL	182	198
Retail | Automobile
Financing Receivable, Past Due [Line Items]
Loans and leases	4,744	8,258
Loans and leases, nonaccrual	48	61
Loans and leases, nonaccrual with no related ACL	6	7
Retail | Education
Financing Receivable, Past Due [Line Items]
Loans and leases	10,812	11,834
Loans and leases, nonaccrual	56	28
Loans and leases, nonaccrual with no related ACL	4	3
Retail | Other retail
Financing Receivable, Past Due [Line Items]
Loans and leases	4,650	5,050
Loans and leases, nonaccrual	68	39
Loans and leases, nonaccrual with no related ACL	1	0
Retail | Financing Receivables, Current
Financing Receivable, Past Due [Line Items]
Loans and leases	67,861	69,775
Retail | Financing Receivables, Current | Residential mortgages
Financing Receivable, Past Due [Line Items]
Loans and leases	32,011	30,499
Retail | Financing Receivables, Current | Home equity
Financing Receivable, Past Due [Line Items]
Loans and leases	16,097	14,640
Retail | Financing Receivables, Current | Automobile
Financing Receivable, Past Due [Line Items]
Loans and leases	4,563	8,005
Retail | Financing Receivables, Current | Education
Financing Receivable, Past Due [Line Items]
Loans and leases	10,686	11,732
Retail | Financing Receivables, Current | Other retail
Financing Receivable, Past Due [Line Items]
Loans and leases	4,504	4,899
Retail | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans and leases	530	606
Retail | Financing Receivables, 30 to 59 Days Past Due | Residential mortgages
Financing Receivable, Past Due [Line Items]
Loans and leases	251	282
Retail | Financing Receivables, 30 to 59 Days Past Due | Home equity
Financing Receivable, Past Due [Line Items]
Loans and leases	88	82
Retail | Financing Receivables, 30 to 59 Days Past Due | Automobile
Financing Receivable, Past Due [Line Items]
Loans and leases	100	144
Retail | Financing Receivables, 30 to 59 Days Past Due | Education
Financing Receivable, Past Due [Line Items]
Loans and leases	45	49
Retail | Financing Receivables, 30 to 59 Days Past Due | Other retail
Financing Receivable, Past Due [Line Items]
Loans and leases	46	49
Retail | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans and leases	207	256
Retail | Financing Receivables, 60 to 89 Days Past Due | Residential mortgages
Financing Receivable, Past Due [Line Items]
Loans and leases	93	118
Retail | Financing Receivables, 60 to 89 Days Past Due | Home equity
Financing Receivable, Past Due [Line Items]
Loans and leases	27	33
Retail | Financing Receivables, 60 to 89 Days Past Due | Automobile
Financing Receivable, Past Due [Line Items]
Loans and leases	33	48
Retail | Financing Receivables, 60 to 89 Days Past Due | Education
Financing Receivable, Past Due [Line Items]
Loans and leases	23	23
Retail | Financing Receivables, 60 to 89 Days Past Due | Other retail
Financing Receivable, Past Due [Line Items]
Loans and leases	31	34
Retail | Financing Receivables, 90 Days or More Past Due
Financing Receivable, Past Due [Line Items]
Loans and leases	182	287
Retail | Financing Receivables, 90 Days or More Past Due | Residential mortgages
Financing Receivable, Past Due [Line Items]
Loans and leases	179	256
Retail | Financing Receivables, 90 Days or More Past Due | Home equity
Financing Receivable, Past Due [Line Items]
Loans and leases	0	0
Retail | Financing Receivables, 90 Days or More Past Due | Automobile
Financing Receivable, Past Due [Line Items]
Loans and leases	0	0
Retail | Financing Receivables, 90 Days or More Past Due | Education
Financing Receivable, Past Due [Line Items]
Loans and leases	2	2
Retail | Financing Receivables, 90 Days or More Past Due | Other retail
Financing Receivable, Past Due [Line Items]
Loans and leases	$ 1	$ 29