CREDIT QUALITY AND THE ALLOWANCE FOR CREDIT LOSSES - Amortized Cost Basis by Credit Quality Indicator (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Total	$ 139,203	$ 145,959
Gross charge-offs
Year one	43	53
Year two	35	66
Year three	72	102
Year four	118	108
Year five	184	55
Prior to year five	253	199
Within the Revolving Period	216	173
Converted to Term	2	1
Total	923	757	$ 434
Commercial
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	8,680	5,669
Year two	4,073	13,841
Year three	11,674	12,883
Year four	9,575	4,966
Year five	3,546	4,476
Prior to year five	8,223	8,133
Within the Revolving Period	23,790	24,399
Converted to Term	215	78
Total	69,776	74,445
Gross charge-offs
Year one	0	1
Year two	0	3
Year three	16	34
Year four	54	60
Year five	146	14
Prior to year five	165	129
Within the Revolving Period	38	44
Converted to Term	0	0
Total	419	285	70
Commercial | Pass
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	8,665	5,600
Year two	3,830	12,303
Year three	9,942	11,393
Year four	8,335	4,000
Year five	2,814	3,441
Prior to year five	6,265	6,194
Within the Revolving Period	22,757	23,008
Converted to Term	70	61
Total	62,678	66,000
Commercial | Special Mention
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	3	59
Year two	79	934
Year three	1,009	894
Year four	598	252
Year five	223	233
Prior to year five	305	373
Within the Revolving Period	291	443
Converted to Term	6	0
Total	2,514	3,188
Commercial | Substandard Accrual
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	12	8
Year two	86	466
Year three	566	540
Year four	522	687
Year five	414	653
Prior to year five	1,128	1,226
Within the Revolving Period	706	892
Converted to Term	133	11
Total	3,567	4,483
Commercial | Nonaccrual
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	0	2
Year two	78	138
Year three	157	56
Year four	120	27
Year five	95	149
Prior to year five	525	340
Within the Revolving Period	36	56
Converted to Term	6	6
Total	1,017	774
Commercial | Commercial and industrial
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	5,956	3,762
Year two	2,679	6,994
Year three	4,567	6,077
Year four	3,490	1,697
Year five	1,087	1,327
Prior to year five	2,422	2,801
Within the Revolving Period	22,265	22,246
Converted to Term	85	70
Total	42,551	44,974
Gross charge-offs
Year one	0	1
Year two	0	3
Year three	15	34
Year four	31	4
Year five	1	1
Prior to year five	22	34
Within the Revolving Period	38	44
Converted to Term	0	0
Total	107	121
Commercial | Commercial and industrial | Pass
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	5,945	3,694
Year two	2,525	6,512
Year three	4,194	5,331
Year four	2,923	1,445
Year five	895	1,147
Prior to year five	2,066	2,299
Within the Revolving Period	21,323	21,033
Converted to Term	66	53
Total	39,937	41,514
Commercial | Commercial and industrial | Special Mention
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	2	59
Year two	79	221
Year three	98	355
Year four	236	30
Year five	48	50
Prior to year five	48	113
Within the Revolving Period	211	368
Converted to Term	0	0
Total	722	1,196
Commercial | Commercial and industrial | Substandard Accrual
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	9	8
Year two	64	189
Year three	207	337
Year four	269	218
Year five	139	125
Prior to year five	253	287
Within the Revolving Period	697	792
Converted to Term	13	11
Total	1,651	1,967
Commercial | Commercial and industrial | Nonaccrual
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	0	1
Year two	11	72
Year three	68	54
Year four	62	4
Year five	5	5
Prior to year five	55	102
Within the Revolving Period	34	53
Converted to Term	6	6
Total	241	297
Commercial | Commercial real estate
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	2,724	1,907
Year two	1,394	6,847
Year three	7,107	6,806
Year four	6,085	3,269
Year five	2,459	3,149
Prior to year five	5,801	5,332
Within the Revolving Period	1,525	2,153
Converted to Term	130	8
Total	27,225	29,471
Gross charge-offs
Year one	0	0
Year two	0	0
Year three	1	0
Year four	23	56
Year five	145	13
Prior to year five	143	95
Within the Revolving Period	0	0
Converted to Term	0	0
Total	312	164
Commercial | Commercial real estate | Pass
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	2,720	1,906
Year two	1,305	5,791
Year three	5,748	6,062
Year four	5,412	2,555
Year five	1,919	2,294
Prior to year five	4,199	3,895
Within the Revolving Period	1,434	1,975
Converted to Term	4	8
Total	22,741	24,486
Commercial | Commercial real estate | Special Mention
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	1	0
Year two	0	713
Year three	911	539
Year four	362	222
Year five	175	183
Prior to year five	257	260
Within the Revolving Period	80	75
Converted to Term	6	0
Total	1,792	1,992
Commercial | Commercial real estate | Substandard Accrual
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	3	0
Year two	22	277
Year three	359	203
Year four	253	469
Year five	275	528
Prior to year five	875	939
Within the Revolving Period	9	100
Converted to Term	120	0
Total	1,916	2,516
Commercial | Commercial real estate | Nonaccrual
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	0	1
Year two	67	66
Year three	89	2
Year four	58	23
Year five	90	144
Prior to year five	470	238
Within the Revolving Period	2	3
Converted to Term	0	0
Total	776	477
Retail
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	4,904	4,817
Year two	4,171	10,219
Year three	8,885	15,492
Year four	13,112	9,169
Year five	7,659	4,095
Prior to year five	11,367	9,675
Within the Revolving Period	18,318	17,008
Converted to Term	1,011	1,039
Total	69,427	71,514
Gross charge-offs
Year one	43	52
Year two	35	63
Year three	56	68
Year four	64	48
Year five	38	41
Prior to year five	88	70
Within the Revolving Period	178	129
Converted to Term	2	1
Total	504	472	$ 364
Retail | Residential mortgages
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	3,459	2,653
Year two	2,554	5,821
Year three	5,621	8,761
Year four	8,318	5,180
Year five	4,833	2,274
Prior to year five	7,941	6,643
Within the Revolving Period	0	0
Converted to Term	0	0
Total	32,726	31,332
Gross charge-offs
Year one	0	0
Year two	0	0
Year three	0	0
Year four	0	1
Year five	0	1
Prior to year five	4	4
Within the Revolving Period	0	0
Converted to Term	0	0
Total	4	6
Retail | Home equity
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	1	1
Year two	3	9
Year three	15	9
Year four	12	7
Year five	6	30
Prior to year five	336	423
Within the Revolving Period	15,115	13,529
Converted to Term	1,007	1,032
Total	16,495	15,040
Gross charge-offs
Year one	0	0
Year two	0	0
Year three	0	0
Year four	0	0
Year five	0	0
Prior to year five	5	3
Within the Revolving Period	11	8
Converted to Term	2	1
Total	18	12
Retail | Automobile
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	0	500
Year two	346	2,335
Year three	1,534	3,444
Year four	2,041	1,207
Year five	592	576
Prior to year five	231	196
Within the Revolving Period	0	0
Converted to Term	0	0
Total	4,744	8,258
Gross charge-offs
Year one	0	3
Year two	6	34
Year three	34	41
Year four	34	14
Year five	10	12
Prior to year five	10	9
Within the Revolving Period	0	0
Converted to Term	0	0
Total	94	113
Retail | Education
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	664	852
Year two	942	1,737
Year three	1,533	3,114
Year four	2,668	2,622
Year five	2,180	1,150
Prior to year five	2,825	2,359
Within the Revolving Period	0	0
Converted to Term	0	0
Total	10,812	11,834
Gross charge-offs
Year one	1	0
Year two	5	5
Year three	12	19
Year four	24	25
Year five	25	17
Prior to year five	59	45
Within the Revolving Period	0	0
Converted to Term	0	0
Total	126	111
Retail | Other retail
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	780	811
Year two	326	317
Year three	182	164
Year four	73	153
Year five	48	65
Prior to year five	34	54
Within the Revolving Period	3,203	3,479
Converted to Term	4	7
Total	4,650	5,050
Gross charge-offs
Year one	42	49
Year two	24	24
Year three	10	8
Year four	6	8
Year five	3	11
Prior to year five	10	9
Within the Revolving Period	167	121
Converted to Term	0	0
Total	262	230
Greater than 800 | Retail
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	1,644	1,449
Year two	1,805	4,351
Year three	4,375	7,913
Year four	7,310	4,939
Year five	4,370	1,913
Prior to year five	5,488	4,466
Within the Revolving Period	6,146	5,578
Converted to Term	200	222
Total	31,338	30,831
Greater than 800 | Retail | Residential mortgages
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	1,230	889
Year two	1,302	3,067
Year three	3,299	5,172
Year four	5,109	3,117
Year five	2,919	1,131
Prior to year five	3,869	3,125
Within the Revolving Period	0	0
Converted to Term	0	0
Total	17,728	16,501
Greater than 800 | Retail | Home equity
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	1	0
Year two	0	4
Year three	3	4
Year four	4	1
Year five	1	4
Prior to year five	76	91
Within the Revolving Period	5,634	5,078
Converted to Term	200	222
Total	5,919	5,404
Greater than 800 | Retail | Automobile
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	0	81
Year two	65	539
Year three	380	1,062
Year four	665	368
Year five	183	162
Prior to year five	58	47
Within the Revolving Period	0	0
Converted to Term	0	0
Total	1,351	2,259
Greater than 800 | Retail | Education
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	227	296
Year two	373	671
Year three	657	1,637
Year four	1,517	1,418
Year five	1,256	600
Prior to year five	1,475	1,185
Within the Revolving Period	0	0
Converted to Term	0	0
Total	5,505	5,807
Greater than 800 | Retail | Other retail
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	186	183
Year two	65	70
Year three	36	38
Year four	15	35
Year five	11	16
Prior to year five	10	18
Within the Revolving Period	512	500
Converted to Term	0	0
Total	835	860
740-799 | Retail
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	2,306	2,093
Year two	1,420	3,393
Year three	2,616	4,696
Year four	3,618	2,682
Year five	2,165	1,150
Prior to year five	2,871	2,456
Within the Revolving Period	6,170	5,671
Converted to Term	225	242
Total	21,391	22,383
740-799 | Retail | Residential mortgages
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	1,757	1,333
Year two	873	1,940
Year three	1,568	2,560
Year four	2,213	1,411
Year five	1,338	592
Prior to year five	1,923	1,625
Within the Revolving Period	0	0
Converted to Term	0	0
Total	9,672	9,461
740-799 | Retail | Home equity
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	0	0
Year two	0	1
Year three	1	2
Year four	2	1
Year five	1	3
Prior to year five	65	82
Within the Revolving Period	5,275	4,708
Converted to Term	224	241
Total	5,568	5,038
740-799 | Retail | Automobile
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	0	134
Year two	92	671
Year three	430	1,038
Year four	581	375
Year five	176	165
Prior to year five	61	52
Within the Revolving Period	0	0
Converted to Term	0	0
Total	1,340	2,435
740-799 | Retail | Education
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	290	368
Year two	359	694
Year three	571	1,050
Year four	804	850
Year five	637	369
Prior to year five	811	678
Within the Revolving Period	0	0
Converted to Term	0	0
Total	3,472	4,009
740-799 | Retail | Other retail
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	259	258
Year two	96	87
Year three	46	46
Year four	18	45
Year five	13	21
Prior to year five	11	19
Within the Revolving Period	895	963
Converted to Term	1	1
Total	1,339	1,440
680-739 | Retail
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	736	872
Year two	609	1,574
Year three	1,159	1,839
Year four	1,358	1,032
Year five	723	541
Prior to year five	1,403	1,314
Within the Revolving Period	3,840	3,666
Converted to Term	184	204
Total	10,012	11,042
680-739 | Retail | Residential mortgages
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	425	367
Year two	281	631
Year three	552	758
Year four	697	466
Year five	385	266
Prior to year five	938	873
Within the Revolving Period	0	0
Converted to Term	0	0
Total	3,278	3,361
680-739 | Retail | Home equity
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	0	1
Year two	0	1
Year three	1	1
Year four	0	2
Year five	1	5
Prior to year five	76	93
Within the Revolving Period	2,995	2,693
Converted to Term	183	202
Total	3,256	2,998
680-739 | Retail | Automobile
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	0	147
Year two	91	577
Year three	338	708
Year four	385	252
Year five	115	118
Prior to year five	45	39
Within the Revolving Period	0	0
Converted to Term	0	0
Total	974	1,841
680-739 | Retail | Education
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	110	143
Year two	150	289
Year three	229	333
Year four	261	273
Year five	211	134
Prior to year five	337	298
Within the Revolving Period	0	0
Converted to Term	0	0
Total	1,298	1,470
680-739 | Retail | Other retail
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	201	214
Year two	87	76
Year three	39	39
Year four	15	39
Year five	11	18
Prior to year five	7	11
Within the Revolving Period	845	973
Converted to Term	1	2
Total	1,206	1,372
620-679 | Retail
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	155	296
Year two	208	565
Year three	401	602
Year four	416	281
Year five	216	232
Prior to year five	697	659
Within the Revolving Period	1,087	1,137
Converted to Term	142	139
Total	3,322	3,911
620-679 | Retail | Residential mortgages
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	31	54
Year two	61	135
Year three	126	165
Year four	151	90
Year five	101	121
Prior to year five	494	445
Within the Revolving Period	0	0
Converted to Term	0	0
Total	964	1,010
620-679 | Retail | Home equity
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	0	0
Year two	1	1
Year three	4	1
Year four	3	2
Year five	2	8
Prior to year five	60	77
Within the Revolving Period	752	718
Converted to Term	141	137
Total	963	944
620-679 | Retail | Automobile
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	0	94
Year two	51	316
Year three	189	345
Year four	194	112
Year five	56	65
Prior to year five	29	26
Within the Revolving Period	0	0
Converted to Term	0	0
Total	519	958
620-679 | Retail | Education
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	27	30
Year two	48	65
Year three	55	68
Year four	58	58
Year five	51	32
Prior to year five	111	107
Within the Revolving Period	0	0
Converted to Term	0	0
Total	350	360
620-679 | Retail | Other retail
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	97	118
Year two	47	48
Year three	27	23
Year four	10	19
Year five	6	6
Prior to year five	3	4
Within the Revolving Period	335	419
Converted to Term	1	2
Total	526	639
Less than 620 | Retail
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	52	89
Year two	129	335
Year three	334	439
Year four	409	233
Year five	184	256
Prior to year five	863	730
Within the Revolving Period	693	583
Converted to Term	260	232
Total	2,924	2,897
Less than 620 | Retail | Residential mortgages
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	15	9
Year two	37	48
Year three	76	104
Year four	147	95
Year five	89	161
Prior to year five	703	561
Within the Revolving Period	0	0
Converted to Term	0	0
Total	1,067	978
Less than 620 | Retail | Home equity
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	0	0
Year two	2	2
Year three	6	1
Year four	3	1
Year five	1	10
Prior to year five	59	80
Within the Revolving Period	459	332
Converted to Term	259	230
Total	789	656
Less than 620 | Retail | Automobile
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	0	44
Year two	47	232
Year three	197	291
Year four	216	100
Year five	62	66
Prior to year five	38	32
Within the Revolving Period	0	0
Converted to Term	0	0
Total	560	765
Less than 620 | Retail | Education
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	5	5
Year two	12	18
Year three	21	25
Year four	28	23
Year five	25	15
Prior to year five	60	55
Within the Revolving Period	0	0
Converted to Term	0	0
Total	151	141
Less than 620 | Retail | Other retail
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	32	31
Year two	31	35
Year three	34	18
Year four	15	14
Year five	7	4
Prior to year five	3	2
Within the Revolving Period	234	251
Converted to Term	1	2
Total	357	357
No FICO available | Retail
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	11	18
Year two	0	1
Year three	0	3
Year four	1	2
Year five	1	3
Prior to year five	45	50
Within the Revolving Period	382	373
Converted to Term	0	0
Total	440	450
No FICO available | Retail | Residential mortgages
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	1	1
Year two	0	0
Year three	0	2
Year four	1	1
Year five	1	3
Prior to year five	14	14
Within the Revolving Period	0	0
Converted to Term	0	0
Total	17	21
No FICO available | Retail | Home equity
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	0	0
Year two	0	0
Year three	0	0
Year four	0	0
Year five	0	0
Prior to year five	0	0
Within the Revolving Period	0	0
Converted to Term	0	0
Total	0	0
No FICO available | Retail | Automobile
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	0	0
Year two	0	0
Year three	0	0
Year four	0	0
Year five	0	0
Prior to year five	0	0
Within the Revolving Period	0	0
Converted to Term	0	0
Total	0	0
No FICO available | Retail | Education
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	5	10
Year two	0	0
Year three	0	1
Year four	0	0
Year five	0	0
Prior to year five	31	36
Within the Revolving Period	0	0
Converted to Term	0	0
Total	36	47
No FICO available | Retail | Other retail
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one	5	7
Year two	0	1
Year three	0	0
Year four	0	1
Year five	0	0
Prior to year five	0	0
Within the Revolving Period	382	373
Converted to Term	0	0
Total	$ 387	$ 382