SECURITIZATIONS AND VARIABLE INTEREST ENTITIES - Mortgage Servicing Rights (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Mortgage servicing rights
Classification of Securitizations
Fair value of capitalized mortgage servicing rights	$ 709,000,000	$ 681,000,000	$ 709,000,000	$ 681,000,000
Principal amount of loans and other financial instruments	53,000,000,000	51,000,000,000	53,000,000,000	51,000,000,000
Capitalized MSRs
Balance, at beginning of period	702,000,000	658,000,000	691,000,000	665,000,000
Originations	19,000,000	19,000,000	36,000,000	31,000,000
Changes in fair value of MSRs due to changes in inputs and assumptions	5,000,000	22,000,000	17,000,000	19,000,000
Other changes	(17,000,000)	(18,000,000)	(35,000,000)	(34,000,000)
Balance, as of June 30	709,000,000	681,000,000	709,000,000	681,000,000
MSR fees
Servicing fees	33,000,000	32,000,000	65,000,000	65,000,000
Late fees	1,000,000	1,000,000	1,000,000	2,000,000
Total MSR fees	34,000,000	33,000,000	66,000,000	67,000,000
Mortgage securitizations - Non-agency-sponsored
Classification of Securitizations
Principal securitized	3,000,000,000.0	1,000,000,000.0	4,100,000,000	2,300,000,000
Proceeds from new securitizations	2,700,000,000	900,000,000	3,700,000,000	2,000,000,000.0
Gains recognized on the securitization	45,500,000	11,300,000	82,000,000	13,700,000
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	1,800,000,000		1,800,000,000		1,700,000,000
Securities transferred to re-securitization entities	6,300,000,000	$ 3,300,000,000	10,700,000,000	$ 8,600,000,000
Market value of retained interest related to re-securitization transaction	942,000,000		942,000,000		930,000,000
Original fair value of re-securitizations deals in which the entity holds a retained interest	$ 73,100,000,000		$ 73,100,000,000		$ 84,100,000,000