SECURITIZATIONS AND VARIABLE INTEREST ENTITIES - Loan Delinquencies and Liquidation Losses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Residential
Variable Interest Entity
Securitized assets	$ 30,400.0		$ 30,400.0		$ 28,200.0
Liquidation losses	(0.7)	$ (200.0)	0.5	$ 4.4
Commercial and other
Variable Interest Entity
Securitized assets	30,500.0		30,500.0		29,900.0
Liquidation losses	0.0	0.0	0.0	0.0
Mortgage securitizations - Non-agency-sponsored
Variable Interest Entity
Securitized assets	60,900.0		60,900.0		58,100.0
Liquidation losses	(0.7)	$ (200.0)	0.5	$ 4.4
Personal loan
Variable Interest Entity
Securitized assets	100.0		100.0
90+ days past due | Residential
Variable Interest Entity
Securitized assets	300.0		300.0		500.0
90+ days past due | Commercial and other
Variable Interest Entity
Securitized assets	0.0		0.0		0.0
90+ days past due | Mortgage securitizations - Non-agency-sponsored
Variable Interest Entity
Securitized assets	$ 300.0		$ 300.0		$ 500.0