LOANS - Corporate Loan Delinquency (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 660,612	$ 657,221
Loans at fair value	5,766	5,360
Lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	300	400
Corporate
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	839	1,898
Total non-accrual	1,261	1,122
Loans, net of unearned income	286,021	289,154
Loans at fair value	5,529	5,123
Corporate | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	697	1,357
Total non-accrual	856	860
Loans, net of unearned income	152,591	147,803
Corporate | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	21	335
Total non-accrual	93	152
Loans, net of unearned income	57,594	64,907
Corporate | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	30	42
Total non-accrual	291	33
Loans, net of unearned income	23,501	21,949
Corporate | Lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	0	1
Total non-accrual	0	10
Loans, net of unearned income	273	354
Corporate | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	91	163
Total non-accrual	21	67
Loans, net of unearned income	46,533	49,018
Corporate | 30–89 days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	572	1,171
Corporate | 30–89 days past due | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	500	763
Corporate | 30–89 days past due | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	10	233
Corporate | 30–89 days past due | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	6	30
Corporate | 30–89 days past due | Lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	0	0
Corporate | 30–89 days past due | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	56	145
Corporate | Equal to and greater than 90 days past due and accruing
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	267	727
Corporate | Equal to and greater than 90 days past due and accruing | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	197	594
Corporate | Equal to and greater than 90 days past due and accruing | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	11	102
Corporate | Equal to and greater than 90 days past due and accruing | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	24	12
Corporate | Equal to and greater than 90 days past due and accruing | Lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	0	1
Corporate | Equal to and greater than 90 days past due and accruing | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	35	18
Corporate | Current
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	278,392	281,011
Corporate | Current | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	151,038	145,586
Corporate | Current | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	57,480	64,420
Corporate | Current | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	23,180	21,874
Corporate | Current | Lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	273	343
Corporate | Current | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 46,421	$ 48,788