LOANS - Corporate Troubled Debt Restructurings (Details) - Corporate - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Financing receivable impaired
Total	$ 19	$ 6	$ 57	$ 83
Period within which default occurred post-modification			1 year
Number of days past due, default status			60 days
TDR balance	150	304	$ 150	304
TDR loans in payment default	0	0	0	0
Commercial and industrial
Financing receivable impaired
Total	11	2	26	75
TDR balance	114	249	114	249
TDR loans in payment default	0	0	0	0
Mortgage and real estate
Financing receivable impaired
Total	1	0	1	4
TDR balance	14	19	14	19
TDR loans in payment default	0	0	0	0
Other
Financing receivable impaired
Total	7	4	30	4
TDR balance	22	36	22	36
TDR loans in payment default	0	0	$ 0	0
Commercial banking loans
Financing receivable impaired
Number of days past due, default status			90 days
TDRs involving changes in the amount and/or timing of principal payments
Financing receivable impaired
Total	1	0	$ 1	0
TDRs involving changes in the amount and/or timing of principal payments | Commercial and industrial
Financing receivable impaired
Total	0	0	0	0
TDRs involving changes in the amount and/or timing of principal payments | Mortgage and real estate
Financing receivable impaired
Total	1	0	1	0
TDRs involving changes in the amount and/or timing of principal payments | Other
Financing receivable impaired
Total	0	0	0	0
TDRs involving changes in the amount and/or timing of interest payments
Financing receivable impaired
Total	0	0	0	0
TDRs involving changes in the amount and/or timing of interest payments | Commercial and industrial
Financing receivable impaired
Total	0	0	0	0
TDRs involving changes in the amount and/or timing of interest payments | Mortgage and real estate
Financing receivable impaired
Total	0	0	0	0
TDRs involving changes in the amount and/or timing of interest payments | Other
Financing receivable impaired
Total	0	0	0	0
TDRs involving changes in the amount and/or timing of both principal and interest payments
Financing receivable impaired
Total	18	6	56	83
TDRs involving changes in the amount and/or timing of both principal and interest payments | Commercial and industrial
Financing receivable impaired
Total	11	2	26	75
TDRs involving changes in the amount and/or timing of both principal and interest payments | Mortgage and real estate
Financing receivable impaired
Total	0	0	0	4
TDRs involving changes in the amount and/or timing of both principal and interest payments | Other
Financing receivable impaired
Total	$ 7	$ 4	$ 30	$ 4