LOANS - Corporate Loan Modifications to Borrowers Experiencing Financial Difficulty (Details) - Corporate loans - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Financing Receivable, Modified [Line Items]
Total modifications balance	$ 141	$ 113	$ 308	$ 170
Commitments to lend	890	492	890	492
Term extension
Financing Receivable, Modified [Line Items]
Total modifications balance	141	111	308	143
Combination: term extension and payment delay
Financing Receivable, Modified [Line Items]
Total modifications balance	0	2	0	27
Commercial and industrial
Financing Receivable, Modified [Line Items]
Total modifications balance	$ 50	$ 66	$ 131	$ 121
Weighted average term extension	9 months	22 months	13 months	21 months
Commercial and industrial | Term extension
Financing Receivable, Modified [Line Items]
Total modifications balance	$ 50	$ 65	$ 131	$ 95
Commercial and industrial | Combination: term extension and payment delay
Financing Receivable, Modified [Line Items]
Total modifications balance	0	1	0	26
Financial institutions
Financing Receivable, Modified [Line Items]
Total modifications balance	0	0	0	0
Financial institutions | Term extension
Financing Receivable, Modified [Line Items]
Total modifications balance	0	0	0	0
Financial institutions | Combination: term extension and payment delay
Financing Receivable, Modified [Line Items]
Total modifications balance	0	0	0	0
Mortgage and real estate
Financing Receivable, Modified [Line Items]
Total modifications balance	$ 91	$ 47	$ 177	$ 49
Weighted average term extension	8 months	24 months	16 months	23 months
Mortgage and real estate | Term extension
Financing Receivable, Modified [Line Items]
Total modifications balance	$ 91	$ 46	$ 177	$ 48
Mortgage and real estate | Combination: term extension and payment delay
Financing Receivable, Modified [Line Items]
Total modifications balance	0	1	0	1
Other
Financing Receivable, Modified [Line Items]
Total modifications balance	0	0	0	0
Other | Term extension
Financing Receivable, Modified [Line Items]
Total modifications balance	0	0	0	0
Other | Combination: term extension and payment delay
Financing Receivable, Modified [Line Items]
Total modifications balance	$ 0	$ 0	$ 0	$ 0