LOANS - Performance of Modified Corporate Loans (Details) - Corporate $ in Millions	Jun. 30, 2023 USD ($)
Financing Receivable, Modified [Line Items]
Total modified loans balance	$ 170
Current
Financing Receivable, Modified [Line Items]
Total modified loans balance	170
30–89 days past due
Financing Receivable, Modified [Line Items]
Total modified loans balance	0
90+ days past due
Financing Receivable, Modified [Line Items]
Total modified loans balance	0
Commercial and industrial
Financing Receivable, Modified [Line Items]
Total modified loans balance	121
Commercial and industrial | Current
Financing Receivable, Modified [Line Items]
Total modified loans balance	121
Commercial and industrial | 30–89 days past due
Financing Receivable, Modified [Line Items]
Total modified loans balance	0
Commercial and industrial | 90+ days past due
Financing Receivable, Modified [Line Items]
Total modified loans balance	0
Financial institutions
Financing Receivable, Modified [Line Items]
Total modified loans balance	0
Financial institutions | Current
Financing Receivable, Modified [Line Items]
Total modified loans balance	0
Financial institutions | 30–89 days past due
Financing Receivable, Modified [Line Items]
Total modified loans balance	0
Financial institutions | 90+ days past due
Financing Receivable, Modified [Line Items]
Total modified loans balance	0
Mortgage and real estate
Financing Receivable, Modified [Line Items]
Total modified loans balance	49
Mortgage and real estate | Current
Financing Receivable, Modified [Line Items]
Total modified loans balance	49
Mortgage and real estate | 30–89 days past due
Financing Receivable, Modified [Line Items]
Total modified loans balance	0
Mortgage and real estate | 90+ days past due
Financing Receivable, Modified [Line Items]
Total modified loans balance	0
Other
Financing Receivable, Modified [Line Items]
Total modified loans balance	0
Other | Current
Financing Receivable, Modified [Line Items]
Total modified loans balance	0
Other | 30–89 days past due
Financing Receivable, Modified [Line Items]
Total modified loans balance	0
Other | 90+ days past due
Financing Receivable, Modified [Line Items]
Total modified loans balance	$ 0