COMMITMENTS AND CONTINGENT LIABILITIES - Funding Agreements (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Federal Home Loan Bank (FHLB)
Restructuring Reserve [Roll Forward]
Outstanding balance, period start	$ 8,501
Issued During the Period	46,499
Repaid During the Period	(46,825)
Long-term Agreements Maturing Within One Year	11
Long-term Agreements Maturing Within Five Years	(11)
Outstanding balance, period end	8,175
Difference related to remaining amortization	3	$ 4
Funding Agreement-Backed Notes Program (FABN)
Restructuring Reserve [Roll Forward]
Outstanding balance, period start	7,085
Issued During the Period	671
Repaid During the Period	(1,000)
Long-term Agreements Maturing Within One Year	0
Long-term Agreements Maturing Within Five Years	0
Foreign Currency Transaction Adjustment	(11)
Outstanding balance, period end	6,745
Difference related to remaining amortization	28	$ 66
Due in one year or less | Federal Home Loan Bank (FHLB)
Restructuring Reserve [Roll Forward]
Outstanding balance, period start	6,130
Issued During the Period	46,499
Repaid During the Period	(46,825)
Long-term Agreements Maturing Within One Year	656
Long-term Agreements Maturing Within Five Years	0
Outstanding balance, period end	6,460
Due in one year or less | Funding Agreement-Backed Notes Program (FABN)
Restructuring Reserve [Roll Forward]
Outstanding balance, period start	1,500
Issued During the Period	0
Repaid During the Period	(1,000)
Long-term Agreements Maturing Within One Year	500
Long-term Agreements Maturing Within Five Years	0
Foreign Currency Transaction Adjustment	0
Outstanding balance, period end	1,000
Due in years two through five | Federal Home Loan Bank (FHLB)
Restructuring Reserve [Roll Forward]
Outstanding balance, period start	1,679
Issued During the Period	0
Repaid During the Period	0
Long-term Agreements Maturing Within One Year	(645)
Long-term Agreements Maturing Within Five Years	0
Outstanding balance, period end	1,034
Due in years two through five | Funding Agreement-Backed Notes Program (FABN)
Restructuring Reserve [Roll Forward]
Outstanding balance, period start	4,000
Issued During the Period	671
Repaid During the Period	0
Long-term Agreements Maturing Within One Year	(500)
Long-term Agreements Maturing Within Five Years	1,285
Foreign Currency Transaction Adjustment	(11)
Outstanding balance, period end	5,445
Due in more than five years | Federal Home Loan Bank (FHLB)
Restructuring Reserve [Roll Forward]
Outstanding balance, period start	692
Issued During the Period	0
Repaid During the Period	0
Long-term Agreements Maturing Within One Year	0
Long-term Agreements Maturing Within Five Years	(11)
Outstanding balance, period end	681
Due in more than five years | Funding Agreement-Backed Notes Program (FABN)
Restructuring Reserve [Roll Forward]
Outstanding balance, period start	1,585
Issued During the Period	0
Repaid During the Period	0
Long-term Agreements Maturing Within One Year	0
Long-term Agreements Maturing Within Five Years	(1,285)
Foreign Currency Transaction Adjustment	0
Outstanding balance, period end	300
Total long-term funding agreements | Federal Home Loan Bank (FHLB)
Restructuring Reserve [Roll Forward]
Outstanding balance, period start	2,371
Issued During the Period	0
Repaid During the Period	0
Long-term Agreements Maturing Within One Year	(645)
Long-term Agreements Maturing Within Five Years	(11)
Outstanding balance, period end	1,715
Total long-term funding agreements | Funding Agreement-Backed Notes Program (FABN)
Restructuring Reserve [Roll Forward]
Outstanding balance, period start	5,585
Issued During the Period	671
Repaid During the Period	0
Long-term Agreements Maturing Within One Year	(500)
Long-term Agreements Maturing Within Five Years	0
Foreign Currency Transaction Adjustment	(11)
Outstanding balance, period end	$ 5,745