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