LOANS - Corporate Loan Delinquency (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Financing Receivable, Credit Quality Indicator [Line Items]
Loans at fair value	$ 7,896	$ 8,040
Unallocated portfolio layer cumulative basis adjustments		(72)
Corporate loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total past due and accruing	553	313
Total non-accrual	2,071	1,377
Loans at fair value	7,870	7,759
Loans net of unearned income, before adjustments	335,224	301,458
Unallocated portfolio layer cumulative basis adjustments	53	(72)
Corporate loans | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Total past due and accruing	229	218
Total non-accrual	903	542
Corporate loans, net of unearned income	153,114	148,674
Corporate loans | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Total past due and accruing	2	8
Total non-accrual	77	73
Corporate loans, net of unearned income	90,140	68,378
Corporate loans | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total past due and accruing	271	8
Total non-accrual	924	567
Corporate loans, net of unearned income	27,551	26,546
Corporate loans | Lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
Total past due and accruing	1	1
Total non-accrual	0	0
Corporate loans, net of unearned income	173	276
Corporate loans | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Total past due and accruing	50	78
Total non-accrual	167	195
Corporate loans, net of unearned income	56,376	49,825
Corporate loans | 30–89 days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Total past due and accruing	337	259
Corporate loans | 30–89 days past due | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Total past due and accruing	191	183
Corporate loans | 30–89 days past due | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Total past due and accruing	2	8
Corporate loans | 30–89 days past due | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total past due and accruing	111	6
Corporate loans | 30–89 days past due | Lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
Total past due and accruing	0	0
Corporate loans | 30–89 days past due | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Total past due and accruing	33	62
Corporate loans | Equal to and greater than 90 days past due and accruing
Financing Receivable, Credit Quality Indicator [Line Items]
Total past due and accruing	216	54
Corporate loans | Equal to and greater than 90 days past due and accruing | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Total past due and accruing	38	35
Corporate loans | Equal to and greater than 90 days past due and accruing | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Total past due and accruing	0	0
Corporate loans | Equal to and greater than 90 days past due and accruing | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total past due and accruing	160	2
Corporate loans | Equal to and greater than 90 days past due and accruing | Lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
Total past due and accruing	1	1
Corporate loans | Equal to and greater than 90 days past due and accruing | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Total past due and accruing	17	16
Corporate loans | Current
Financing Receivable, Credit Quality Indicator [Line Items]
Corporate loans, net of unearned income	324,730	292,009
Corporate loans | Current | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Corporate loans, net of unearned income	151,982	147,914
Corporate loans | Current | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Corporate loans, net of unearned income	90,061	68,297
Corporate loans | Current | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Corporate loans, net of unearned income	26,356	25,971
Corporate loans | Current | Lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
Corporate loans, net of unearned income	172	275
Corporate loans | Current | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Corporate loans, net of unearned income	$ 56,159	$ 49,552