LOANS - Corporate Loan Delinquency (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 657,333	$ 667,767
Loans held at fair value	4,536	6,082
Lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	400	500
Corporate
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	1,889	1,895
Total non-accrual	1,655	1,553
Loans, net of unearned income	301,728	291,233
Loans held at fair value	4,528	6,070
Corporate | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	1,277	1,311
Total non-accrual	1,407	1,263
Loans, net of unearned income	161,338	147,004
Corporate | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	466	486
Total non-accrual	78	2
Loans, net of unearned income	70,448	71,767
Corporate | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	31	2
Total non-accrual	77	136
Loans, net of unearned income	21,761	20,291
Corporate | Lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	0	0
Total non-accrual	11	14
Loans, net of unearned income	432	455
Corporate | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	115	96
Total non-accrual	82	138
Loans, net of unearned income	43,221	45,646
Corporate | 30 to 89 days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	1,320	1,470
Corporate | 30 to 89 days past due | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	919	1,072
Corporate | 30 to 89 days past due | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	304	320
Corporate | 30 to 89 days past due | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	11	1
Corporate | 30 to 89 days past due | Lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	0	0
Corporate | 30 to 89 days past due | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	86	77
Corporate | Equal to and greater than 90 days past due and accruing
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	569	425
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	358	239
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	162	166
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	20	1
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	0
Corporate | Equal to and greater than 90 days past due and accruing | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Past due and accruing	29	19
Corporate | Current
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	293,656	281,715
Corporate | Current | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	158,654	144,430
Corporate | Current | Financial institutions
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	69,904	71,279
Corporate | Current | Mortgage and real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	21,653	20,153
Corporate | Current | Lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	421	441
Corporate | Current | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 43,024	$ 45,412