ALLOWANCE FOR CREDIT LOSSES - Schedule of Allowance for Credit Losses for Other Assets (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Financing Receivable, Other Assets, Allowance For Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period	$ 53	$ 55
Gross credit losses	(7)	0
Gross recoveries	0	0
Net credit losses (NCLs)	(7)	0
Net reserve builds (releases)	(11)	9
Total provision for credit losses	(4)	9
Other, net	1	(1)
Allowance for credit losses at end of period	43	63
Deposits with banks
Financing Receivable, Other Assets, Allowance For Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period	21	20
Gross credit losses	0	0
Gross recoveries		0
Net credit losses (NCLs)	0	0
Net reserve builds (releases)	(6)	9
Total provision for credit losses	(6)	9
Other, net	0	(1)
Allowance for credit losses at end of period	15	28
Securities borrowed and purchased under agreements to resell
Financing Receivable, Other Assets, Allowance For Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period	6	10
Gross credit losses	0	0
Gross recoveries	0	0
Net credit losses (NCLs)	0	0
Net reserve builds (releases)	(2)	(5)
Total provision for credit losses	(2)	(5)
Other, net	0	0
Allowance for credit losses at end of period	4	5
Brokerage receivables
Financing Receivable, Other Assets, Allowance For Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period	0	0
Gross credit losses	0	0
Gross recoveries	0	0
Net credit losses (NCLs)	0	0
Net reserve builds (releases)	0	0
Total provision for credit losses	0	0
Other, net	0	0
Allowance for credit losses at end of period	0	0
All other assets
Financing Receivable, Other Assets, Allowance For Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period	26	25
Gross credit losses	(7)	0
Gross recoveries	0	0
Net credit losses (NCLs)	(7)	0
Net reserve builds (releases)	(3)	5
Total provision for credit losses	4	5
Other, net	1	0
Allowance for credit losses at end of period	$ 24	$ 30