LOANS - Consumer Loans Credit Scores (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	$ 733,905	$ 694,488
Unallocated portfolio layer cumulative basis adjustments		(72)
Consumer loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	398,628	393,102
Unallocated portfolio layer cumulative basis adjustments	592	(224)
Consumer loans | In North America offices
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	320,595	321,948
Consumer loans | In North America offices | 90+ days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	2,996	3,162
Consumer loans | In North America offices | 90+ days past due | Banking
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	25,200	25,900
Consumer loans | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	77,441	71,378
Consumer loans | In offices outside North America | 90+ days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	399	310
Consumer loans | In offices outside North America | 90+ days past due | Banking
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	21,600	17,600
Consumer loans | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	319,191	320,631
Consumer loans | Residential mortgages | In North America offices
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	117,799	114,593
Consumer loans | Residential mortgages | In North America offices | 90+ days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	548	349
Consumer loans | Residential mortgages | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	24,078	24,456
Consumer loans | Residential mortgages | In offices outside North America | 90+ days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	73	60
Consumer loans | Residential mortgages | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	117,799	114,593
Consumer loans | Home equity loans | In North America offices
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	2,916	3,141
Consumer loans | Home equity loans | In North America offices | 90+ days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	40	58
Consumer loans | Home equity loans | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	2,916	3,141
Consumer loans | Credit cards | In North America offices
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	167,446	171,059
Consumer loans | Credit cards | In North America offices | 90+ days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	2,377	2,705
Consumer loans | Credit cards | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving loans converted to term loans	50	33
Total loans, net of unearned income	13,754	12,927
Consumer loans | Credit cards | In offices outside North America | 90+ days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	286	214
Consumer loans | Credit cards | Canada
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	572	562
Consumer loans | Credit cards | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	166,874	170,497
Consumer loans | Personal, small business and other
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving loans converted to term loans	16	22
Consumer loans | Personal, small business and other | In North America offices
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	32,434	33,155
Consumer loans | Personal, small business and other | In North America offices | 90+ days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	31	50
Consumer loans | Personal, small business and other | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	39,609	$ 33,995
Consumer loans | Personal, small business and other | In offices outside North America | Internal Investment Grade
Financing Receivable, Credit Quality Indicator [Line Items]
Percentage of loans rated investment grade		83.00%
Consumer loans | Personal, small business and other | In offices outside North America | 90+ days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	40	$ 36
Consumer loans | Personal, small business and other | Canada
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	833	755
Consumer loans | Personal, small business and other | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	31,602	32,400
Consumer loans | Classifiably Managed and Delinquency Managed | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	79,400	72,500
Consumer loans | Less than 660 | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	28,159	27,952
Consumer loans | Less than 660 | Residential mortgages | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	91	123
One year prior to current fiscal year	151	223
Two years prior to current fiscal year	210	354
Three years prior to current fiscal year	344	312
Four years prior to current fiscal year	346	298
Prior	1,715	1,473
Total loans, net of unearned income	2,857	2,783
Consumer loans | Less than 660 | Home equity line of credit (pre-reset) | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	240	266
Consumer loans | Less than 660 | Home equity line of credit (post-reset) | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	60	58
Consumer loans | Less than 660 | Home equity term loans | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
One year prior to current fiscal year	0	0
Two years prior to current fiscal year	0	0
Three years prior to current fiscal year	0	0
Four years prior to current fiscal year	0	0
Prior	40	45
Total loans, net of unearned income	40	45
Consumer loans | Less than 660 | Home equity loans | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	340	369
Consumer loans | Less than 660 | Credit cards | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	22,826	22,855
Consumer loans | Less than 660 | Credit cards | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving loans converted to term loans	1,660	1,462
Total loans, net of unearned income	24,486	24,317
Consumer loans | Less than 660 | Personal, small business and other | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	47	96
One year prior to current fiscal year	146	132
Two years prior to current fiscal year	101	131
Three years prior to current fiscal year	79	28
Four years prior to current fiscal year	13	2
Prior	90	94
Total loans, net of unearned income	476	483
Consumer loans | 660 to 739 | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	78,270	79,930
Consumer loans | 660 to 739 | Residential mortgages | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1,603	2,213
One year prior to current fiscal year	1,770	2,451
Two years prior to current fiscal year	2,111	3,272
Three years prior to current fiscal year	3,022	2,745
Four years prior to current fiscal year	2,488	1,990
Prior	6,264	5,034
Total loans, net of unearned income	17,258	17,705
Consumer loans | 660 to 739 | Home equity line of credit (pre-reset) | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	702	764
Consumer loans | 660 to 739 | Home equity line of credit (post-reset) | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	76	80
Consumer loans | 660 to 739 | Home equity term loans | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
One year prior to current fiscal year	0	0
Two years prior to current fiscal year	0	0
Three years prior to current fiscal year	0	0
Four years prior to current fiscal year	0	1
Prior	75	86
Total loans, net of unearned income	75	87
Consumer loans | 660 to 739 | Home equity loans | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	853	931
Consumer loans | 660 to 739 | Credit cards | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	58,363	59,574
Consumer loans | 660 to 739 | Credit cards | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving loans converted to term loans	805	668
Total loans, net of unearned income	59,168	60,242
Consumer loans | 660 to 739 | Personal, small business and other | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	219	398
One year prior to current fiscal year	349	282
Two years prior to current fiscal year	173	180
Three years prior to current fiscal year	95	38
Four years prior to current fiscal year	17	2
Prior	138	152
Total loans, net of unearned income	991	1,052
Consumer loans | Greater than or equal to 740 | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	175,576	174,872
Consumer loans | Greater than or equal to 740 | Residential mortgages | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	9,348	10,308
One year prior to current fiscal year	8,988	12,936
Two years prior to current fiscal year	11,884	16,034
Three years prior to current fiscal year	15,372	14,651
Four years prior to current fiscal year	14,117	12,245
Prior	30,830	20,573
Total loans, net of unearned income	90,539	86,747
Consumer loans | Greater than or equal to 740 | Home equity line of credit (pre-reset) | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	1,512	1,597
Consumer loans | Greater than or equal to 740 | Home equity line of credit (post-reset) | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	70	75
Consumer loans | Greater than or equal to 740 | Home equity term loans | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
One year prior to current fiscal year	0	0
Two years prior to current fiscal year	0	0
Three years prior to current fiscal year	0	1
Four years prior to current fiscal year	1	2
Prior	96	111
Total loans, net of unearned income	97	114
Consumer loans | Greater than or equal to 740 | Home equity loans | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	1,679	1,786
Consumer loans | Greater than or equal to 740 | Credit cards | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	81,063	83,935
Consumer loans | Greater than or equal to 740 | Credit cards | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving loans converted to term loans	155	129
Total loans, net of unearned income	81,218	84,064
Consumer loans | Greater than or equal to 740 | Personal, small business and other | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	754	1,219
One year prior to current fiscal year	789	577
Two years prior to current fiscal year	307	271
Three years prior to current fiscal year	133	54
Four years prior to current fiscal year	21	4
Prior	136	150
Total loans, net of unearned income	2,140	2,275
Consumer loans | Classifiably managed | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	21,562	17,553
Consumer loans | Classifiably managed | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	25,223	25,860
Consumer loans | Classifiably managed | Residential mortgages | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	0	0
Consumer loans | Classifiably managed | Residential mortgages | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	0	0
Consumer loans | Classifiably managed | Home equity loans | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	0	0
Consumer loans | Classifiably managed | Credit cards | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	0	0
Consumer loans | Classifiably managed | Credit cards | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	0	0
Consumer loans | Classifiably managed | Personal, small business and other | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	21,562	17,553
Consumer loans | Classifiably managed | Personal, small business and other | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	25,223	25,860
Consumer loans | FICO not available | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	11,963	12,017
Consumer loans | FICO not available | Residential mortgages | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	7,145	7,358
Consumer loans | FICO not available | Home equity loans | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	44	55
Consumer loans | FICO not available | Credit cards | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	2,002	1,874
Consumer loans | FICO not available | Personal, small business and other | U.S. plans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	$ 2,772	$ 2,730