ALLOWANCE FOR CREDIT LOSSES - Schedule of Allowance for Credit Losses for HTM Debt Securities (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses on HTM debt securities at beginning of quarter	$ 120	$ 87
Gross credit losses	0	0
Gross recoveries	0	0
Net credit losses (NCLs)	0	0
Net reserve builds (releases)	(17)	(2)
Net specific reserve builds (releases)	0
Total provision for credit losses on HTM debt securities	(17)	(2)
Other, net	1	0
Allowance for credit losses on HTM debt securities at end of quarter	104	85
Mortgage-backed securities
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses on HTM debt securities at beginning of quarter	1	6
Gross credit losses	0	0
Gross recoveries	0	0
Net credit losses (NCLs)	0	0
Net reserve builds (releases)	2	(2)
Net specific reserve builds (releases)	0
Total provision for credit losses on HTM debt securities	2	(2)
Other, net	(1)	0
Allowance for credit losses on HTM debt securities at end of quarter	2	4
State and municipal
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses on HTM debt securities at beginning of quarter	113	75
Gross credit losses	0	0
Gross recoveries	0	0
Net credit losses (NCLs)	0	0
Net reserve builds (releases)	(15)	4
Net specific reserve builds (releases)	0	0
Total provision for credit losses on HTM debt securities	(15)	4
Other, net	0	0
Allowance for credit losses on HTM debt securities at end of quarter	98	79
Foreign government
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses on HTM debt securities at beginning of quarter	3	4
Gross credit losses	0	0
Gross recoveries	0	0
Net credit losses (NCLs)	0	0
Net reserve builds (releases)	0	(2)
Net specific reserve builds (releases)	0	0
Total provision for credit losses on HTM debt securities	0	(2)
Other, net	0	0
Allowance for credit losses on HTM debt securities at end of quarter	3	2
Asset-backed
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses on HTM debt securities at beginning of quarter	3	2
Gross credit losses	0	0
Gross recoveries	0	0
Net credit losses (NCLs)	0	0
Net reserve builds (releases)	(4)	(2)
Net specific reserve builds (releases)	0	0
Total provision for credit losses on HTM debt securities	(4)	(2)
Other, net	2	0
Allowance for credit losses on HTM debt securities at end of quarter	$ 1	$ 0