SECURITIZATIONS AND VARIABLE INTEREST ENTITIES - Mortgage Servicing Rights (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Mortgage servicing rights
Classification of Securitizations
Fair value of capitalized mortgage servicing rights	$ 683,000,000	$ 729,000,000	$ 683,000,000	$ 729,000,000
Principal amount of loans and other financial instruments	55,000,000,000	52,000,000,000	55,000,000,000	52,000,000,000
Capitalized MSRs
Balance, at beginning of period	709,000,000	681,000,000	691,000,000	665,000,000
Originations	32,000,000	23,000,000	68,000,000	54,000,000
Changes in fair value of MSRs due to changes in inputs and assumptions	(40,000,000)	42,000,000	(23,000,000)	61,000,000
Other changes	(18,000,000)	(17,000,000)	(53,000,000)	(51,000,000)
Balance, as of September 30	683,000,000	729,000,000	683,000,000	729,000,000
MSR fees
Servicing fees	30,000,000	32,000,000	95,000,000	97,000,000
Late fees	0	1,000,000	1,000,000	3,000,000
Total MSR fees	30,000,000	33,000,000	96,000,000	100,000,000
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	2,300,000,000		2,300,000,000		1,700,000,000
Securities transferred to re-securitization entities	6,300,000,000	$ 4,300,000,000	17,000,000,000	$ 12,800,000,000
Market value of retained interest related to re-securitization transaction	1,500,000,000		1,500,000,000		930,000,000
Original fair value of re-securitizations deals in which the entity holds a retained interest	$ 79,000,000,000		$ 79,000,000,000		$ 84,100,000,000