SECURITIZATIONS AND VARIABLE INTEREST ENTITIES - Loan Delinquencies and Liquidation Losses (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Residential
Variable Interest Entity
Securitized assets	$ 26,600.0		$ 28,200.0
Liquidation losses	0.7	$ 2,300.0
Commercial and other
Variable Interest Entity
Securitized assets	29,700.0		29,900.0
Liquidation losses	0.0	0.0
Mortgage securitizations - Non-agency-sponsored
Variable Interest Entity
Securitized assets	56,300.0		58,100.0
Liquidation losses	0.7	$ 2,300.0
Personal loan
Variable Interest Entity
Securitized assets	100.0
90+ days past due | Residential
Variable Interest Entity
Securitized assets	400.0		500.0
90+ days past due | Commercial and other
Variable Interest Entity
Securitized assets	0.0		0.0
90+ days past due | Mortgage securitizations - Non-agency-sponsored
Variable Interest Entity
Securitized assets	$ 400.0		$ 500.0