LOANS - Corporate Loan Modifications to Borrowers Experiencing Financial Difficulty (Details) - Corporate loans - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Financing Receivable, Modified [Line Items]
Total modifications balance	$ 53	$ 60	$ 237	$ 178
Commitments to lend	924	1,000	924	1,000
Term extension
Financing Receivable, Modified [Line Items]
Total modifications balance	53	60	237	154
Combination: term extension and payment delay
Financing Receivable, Modified [Line Items]
Total modifications balance	0	0	0	24
Commercial and industrial
Financing Receivable, Modified [Line Items]
Total modifications balance	$ 4	$ 25	$ 107	$ 93
Weighted average term extension	6 months	22 months	11 months	28 months
Commercial and industrial | Term extension
Financing Receivable, Modified [Line Items]
Total modifications balance	$ 4	$ 25	$ 107	$ 70
Commercial and industrial | Combination: term extension and payment delay
Financing Receivable, Modified [Line Items]
Total modifications balance	0	0	0	23
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	$ 49	$ 35	$ 130	$ 85
Weighted average term extension	6 months	55 months	7 months	37 months
Mortgage and real estate | Term extension
Financing Receivable, Modified [Line Items]
Total modifications balance	$ 49	$ 35	$ 130	$ 84
Mortgage and real estate | Combination: term extension and payment delay
Financing Receivable, Modified [Line Items]
Total modifications balance	0	0	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