LOANS - Loan-to-Value Ratios Consumer Loans (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 | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	319,191	320,631
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 | Less than or equal to 80% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	111,243	107,142
Consumer loans | Greater than 80% but less than or equal to 100% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	8,331	8,742
Consumer loans | Greater than 100% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	118	158
Consumer loans | LTV not available | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	1,023	1,692
Consumer loans | Total | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	120,715	117,734
Consumer loans | Residential mortgages | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	117,799	114,593
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 | Less than or equal to 80% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	8,458	9,196
One year prior to current fiscal year	9,059	13,973
Two years prior to current fiscal year	13,389	18,546
Three years prior to current fiscal year	18,429	18,247
Four years prior to current fiscal year	17,742	15,434
Prior	41,403	28,797
Total loans, net of unearned income	108,480	104,193
Consumer loans | Residential mortgages | Less than or equal to 80% | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1,847	2,808
One year prior to current fiscal year	2,805	2,406
Two years prior to current fiscal year	2,100	2,579
Three years prior to current fiscal year	2,337	2,505
Four years prior to current fiscal year	2,244	1,739
Prior	8,107	7,642
Total loans, net of unearned income	$ 19,440	$ 19,679
Loan to value ratio	57.00%	58.00%
Consumer loans | Residential mortgages | Greater than 80% but less than or equal to 100% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	$ 2,741	$ 3,550
One year prior to current fiscal year	2,166	2,036
Two years prior to current fiscal year	1,289	2,078
Three years prior to current fiscal year	1,397	472
Four years prior to current fiscal year	281	226
Prior	402	351
Total loans, net of unearned income	8,276	8,713
Consumer loans | Residential mortgages | Greater than 80% but less than or equal to 100% | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	165	421
One year prior to current fiscal year	341	654
Two years prior to current fiscal year	598	462
Three years prior to current fiscal year	556	426
Four years prior to current fiscal year	534	326
Prior	449	148
Total loans, net of unearned income	2,643	2,437
Consumer loans | Residential mortgages | Greater than 100% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	1
One year prior to current fiscal year	1	2
Two years prior to current fiscal year	3	42
Three years prior to current fiscal year	24	33
Four years prior to current fiscal year	6	1
Prior	28	25
Total loans, net of unearned income	62	104
Consumer loans | Residential mortgages | Greater than 100% | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
One year prior to current fiscal year	0	412
Two years prior to current fiscal year	346	698
Three years prior to current fiscal year	539	657
Four years prior to current fiscal year	499	176
Prior	127	8
Total loans, net of unearned income	1,511	1,951
Consumer loans | Residential mortgages | LTV not available | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	981	1,583
Consumer loans | Residential mortgages | LTV not available | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	484	389
Consumer loans | Home equity loans | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	2,916	3,141
Consumer loans | Home equity loans | Less than or equal to 80% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	2,763	2,949
Consumer loans | Home equity loans | Greater than 80% but less than or equal to 100% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	55	29
Consumer loans | Home equity loans | Greater than 100% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	56	54
Consumer loans | Home equity loans | LTV not available | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	42	109
Consumer loans | Home equity line of credit (pre-reset) | Less than or equal to 80% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	2,380	2,514
Consumer loans | Home equity line of credit (pre-reset) | Greater than 80% but less than or equal to 100% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	42	26
Consumer loans | Home equity line of credit (pre-reset) | Greater than 100% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	34	45
Consumer loans | Home equity line of credit (post-reset) | Less than or equal to 80% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	383	435
Consumer loans | Home equity line of credit (post-reset) | Greater than 80% but less than or equal to 100% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	13	3
Consumer loans | Home equity line of credit (post-reset) | Greater than 100% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans, net of unearned income	$ 22	$ 9