LOANS - Corporate Troubled Debt Restructurings (Details) - Corporate - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Financing receivable impaired
Total	$ 26	$ 57	$ 38	$ 80
Period within which default occurred post-modification			1 year
Number of days past due, default status			60 days
TDR balance	203	416	$ 203	416
TDR loans in payment default	0	0	0	0
Commercial and industrial
Financing receivable impaired
Total	3	52	15	73
TDR balance	148	298	148	298
TDR loans in payment default	0	0	0	0
Mortgage and real estate
Financing receivable impaired
Total		5		6
TDR balance	16	80	16	80
TDR loans in payment default	0	0	0	0
Other
Financing receivable impaired
Total	23	0	23	1
TDR balance	39	38	39	38
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	0	0	$ 1	1
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		0		0
TDRs involving changes in the amount and/or timing of principal payments | Other
Financing receivable impaired
Total	0	0	1	1
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
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	26	57	37	79
TDRs involving changes in the amount and/or timing of both principal and interest payments | Commercial and industrial
Financing receivable impaired
Total	3	52	15	73
TDRs involving changes in the amount and/or timing of both principal and interest payments | Mortgage and real estate
Financing receivable impaired
Total		5		6
TDRs involving changes in the amount and/or timing of both principal and interest payments | Other
Financing receivable impaired
Total	$ 23	$ 0	$ 22	$ 0