LOANS - Corporate Loan Delinquency (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 651,995	$ 657,221
Loans at fair value	5,134	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	1,497	1,898
Total non-accrual	1,213	1,122
Loans, net of unearned income	288,299	289,154
Loans at fair value	4,896	5,123
Corporate | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	1,000	1,357
Total non-accrual	909	860
Loans, net of unearned income	150,330	147,803
Corporate | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	126	335
Total non-accrual	158	152
Loans, net of unearned income	60,434	64,907
Corporate | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	255	42
Total non-accrual	89	33
Loans, net of unearned income	23,478	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	348	354
Corporate | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	116	163
Total non-accrual	57	67
Loans, net of unearned income	48,813	49,018
Corporate | 30–89 days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	858	1,171
Corporate | 30–89 days past due | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	564	763
Corporate | 30–89 days past due | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	37	233
Corporate | 30–89 days past due | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	188	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	69	145
Corporate | Equal to and greater than 90 days past due and accruing
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	639	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	436	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	89	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	67	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	47	18
Corporate | Current
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	280,693	281,011
Corporate | Current | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	148,421	145,586
Corporate | Current | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	60,150	64,420
Corporate | Current | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	23,134	21,874
Corporate | Current | Lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	348	343
Corporate | Current | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 48,640	$ 48,788