ALLOWANCE FOR CREDIT LOSSES - Schedule of Allowance for Credit Losses for Other Assets (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Financing Receivable, Other Assets, Allowance For Credit Loss [Roll Forward]
Allowance for credit losses on other assets at beginning of quarter	$ 43	$ 63	$ 53	$ 55
Gross credit losses	(8)	0	(15)	0
Gross recoveries	2	0	2	0
Net credit losses (NCLs)	(6)	0	(13)	0
Net reserve builds (releases)	1	(3)	(10)	6
Total provision for credit losses	7	(3)	3	6
Other, net	30	0	31	(1)
Allowance for credit losses on other assets at end of quarter	74	60	74	60
Institutional Clients Group
Financing Receivable, Other Assets, Allowance For Credit Loss [Roll Forward]
Other, net			30
Deposits with banks
Financing Receivable, Other Assets, Allowance For Credit Loss [Roll Forward]
Allowance for credit losses on other assets at beginning of quarter	15	28	21	20
Gross credit losses	0	0	0	0
Gross recoveries	0	0	0	0
Net credit losses (NCLs)	0	0	0	0
Net reserve builds (releases)	2	(4)	(4)	5
Total provision for credit losses	2	(4)	(4)	5
Other, net	0	0	0	(1)
Allowance for credit losses on other assets at end of quarter	17	24	17	24
Securities borrowed and purchased under agreements to resell
Financing Receivable, Other Assets, Allowance For Credit Loss [Roll Forward]
Allowance for credit losses on other assets at beginning of quarter	4	5	6	10
Gross credit losses	0	0	0	0
Gross recoveries	0	0	0	0
Net credit losses (NCLs)	0	0	0	0
Net reserve builds (releases)	(8)	3	(10)	(2)
Total provision for credit losses	(8)	3	(10)	(2)
Other, net	31	0	31	0
Allowance for credit losses on other assets at end of quarter	27	8	27	8
Brokerage receivables
Financing Receivable, Other Assets, Allowance For Credit Loss [Roll Forward]
Allowance for credit losses on other assets at beginning of quarter	0	0	0	0
Gross credit losses	0	0	0	0
Gross recoveries	0	0	0	0
Net credit losses (NCLs)	0	0	0	0
Net reserve builds (releases)	0	0	0	0
Total provision for credit losses	0	0	0	0
Other, net	0	0	0	0
Allowance for credit losses on other assets at end of quarter	0	0	0	0
All other assets
Financing Receivable, Other Assets, Allowance For Credit Loss [Roll Forward]
Allowance for credit losses on other assets at beginning of quarter	24	30	26	25
Gross credit losses	(8)	0	(15)	0
Gross recoveries	2	0	2	0
Net credit losses (NCLs)	(6)	0	(13)	0
Net reserve builds (releases)	7	(2)	4	3
Total provision for credit losses	13	(2)	17	3
Other, net	(1)	0	0	0
Allowance for credit losses on other assets at end of quarter	$ 30	$ 28	$ 30	$ 28