SECURITIZATIONS AND VARIABLE INTEREST ENTITIES - Mortgage Servicing Rights (Details) - USD ($)	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Mortgage servicing rights
Classification of Securitizations
Fair value of capitalized mortgage servicing rights	$ 658,000,000	$ 519,000,000
Principal amount of loans and other financial instruments	50,000,000,000	47,000,000,000
Capitalized MSRs
Balance, at beginning of period	665,000,000	404,000,000
Originations	12,000,000	34,000,000
Changes in fair value of MSRs due to changes in inputs and assumptions	(3,000,000)	98,000,000
Other changes	(16,000,000)	(17,000,000)
Sale of MSRs	0	0
Balance, as of March 31	658,000,000	519,000,000
MSR fees
Servicing fees	33,000,000	29,000,000
Late fees	1,000,000	1,000,000
Total MSR fees	34,000,000	30,000,000
Mortgage securitizations - Non-agency-sponsored
Re-securitizations
Fair value of re-securitizations deals in which the entity holds a retained interest	0		$ 0
Mortgage securitizations - U.S. agency-sponsored
Re-securitizations
Fair value of re-securitizations deals in which the entity holds a retained interest	1,400,000,000		1,400,000,000
Securities transferred to re-securitization entities	5,300,000,000	$ 9,300,000,000
Market value of retained interest related to re-securitization transaction	268,000,000		801,000,000
Original fair value of re-securitizations deals in which the entity holds a retained interest	$ 86,600,000,000		$ 79,400,000,000