LOANS - Corporate Troubled Debt Restructurings (Details) - Corporate loans - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Financing Receivable, Modified [Line Items]
Troubled debt restructurings		$ 19		$ 57
Total modifications balance	$ 60		$ 178
Commercial and industrial
Financing Receivable, Modified [Line Items]
Troubled debt restructurings		11		26
Total modifications balance	25		93
Mortgage and real estate
Financing Receivable, Modified [Line Items]
Total modifications balance	35	1	85	1
Other
Financing Receivable, Modified [Line Items]
Troubled debt restructurings		7		30
Total modifications balance	0		0
TDRs involving changes in the amount and/or timing of principal payments
Financing Receivable, Modified [Line Items]
Troubled debt restructurings		1		1
TDRs involving changes in the amount and/or timing of principal payments | Commercial and industrial
Financing Receivable, Modified [Line Items]
Troubled debt restructurings		0		0
TDRs involving changes in the amount and/or timing of principal payments | Other
Financing Receivable, Modified [Line Items]
Troubled debt restructurings		0		0
TDRs involving vhanges in the amount and/or timing of interest payments
Financing Receivable, Modified [Line Items]
Troubled debt restructurings		0		0
TDRs involving vhanges in the amount and/or timing of interest payments | Commercial and industrial
Financing Receivable, Modified [Line Items]
Troubled debt restructurings		0		0
TDRs involving vhanges in the amount and/or timing of interest payments | Other
Financing Receivable, Modified [Line Items]
Troubled debt restructurings		0		0
TDRs invovling changes in the amount and/or timing of both principal and interest payments
Financing Receivable, Modified [Line Items]
Troubled debt restructurings		18		56
TDRs invovling changes in the amount and/or timing of both principal and interest payments | Commercial and industrial
Financing Receivable, Modified [Line Items]
Troubled debt restructurings		11		26
TDRs invovling changes in the amount and/or timing of both principal and interest payments | Other
Financing Receivable, Modified [Line Items]
Troubled debt restructurings		7		30
Term extension
Financing Receivable, Modified [Line Items]
Total modifications balance	60		154
Term extension | Commercial and industrial
Financing Receivable, Modified [Line Items]
Total modifications balance	25		70
Term extension | Mortgage and real estate
Financing Receivable, Modified [Line Items]
Total modifications balance	35	1	84	1
Term extension | Other
Financing Receivable, Modified [Line Items]
Total modifications balance	0		0
Combination: Term extension and payment delay(4)
Financing Receivable, Modified [Line Items]
Total modifications balance	0		24
Combination: Term extension and payment delay(4) | Commercial and industrial
Financing Receivable, Modified [Line Items]
Total modifications balance	0		23
Combination: Term extension and payment delay(4) | Mortgage and real estate
Financing Receivable, Modified [Line Items]
Total modifications balance	0	$ 0	1	$ 0
Combination: Term extension and payment delay(4) | Other
Financing Receivable, Modified [Line Items]
Total modifications balance	$ 0		$ 0