SECURITIZATIONS AND VARIABLE INTEREST ENTITIES - Mortgage Servicing Rights (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Mortgage servicing rights
Classification of Securitizations
Fair value of capitalized mortgage servicing rights	$ 681,000,000	$ 600,000,000	$ 681,000,000	$ 600,000,000
Principal amount of loans and other financial instruments	51,000,000,000	49,000,000,000	51,000,000,000	49,000,000,000
Capitalized MSRs
Balance, at beginning of period	658,000,000	520,000,000	665,000,000	404,000,000
Originations	19,000,000	35,000,000	31,000,000	69,000,000
Changes in fair value of MSRs due to changes in inputs and assumptions	22,000,000	59,000,000	19,000,000	158,000,000
Other changes	(18,000,000)	(14,000,000)	(34,000,000)	(31,000,000)
Sale of MSRs	0	0	0	0
Balance, as of June 30	681,000,000	600,000,000	681,000,000	600,000,000
MSR fees
Servicing fees	32,000,000	30,000,000	65,000,000	59,000,000
Late fees	1,000,000	1,000,000	2,000,000	2,000,000
Total MSR fees	33,000,000	31,000,000	67,000,000	61,000,000
Mortgage securitizations - Non-agency-sponsored
Re-securitizations
Fair value of re-securitizations deals in which the entity holds a retained interest	0		0		$ 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		1,400,000,000
Securities transferred to re-securitization entities	3,300,000,000	$ 5,600,000,000	8,600,000,000	$ 14,900,000,000
Market value of retained interest related to re-securitization transaction	402,000,000		402,000,000		801,000,000
Original fair value of re-securitizations deals in which the entity holds a retained interest	$ 86,800,000,000		$ 86,800,000,000		$ 79,400,000,000