SECURITIZATIONS AND VARIABLE INTEREST ENTITIES - Loan Delinquencies and Liquidation Losses (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Residential mortgages
Variable Interest Entity
Securitized assets	$ 30,000.0		$ 30,000.0		$ 30,800.0
Liquidation losses	0.0	$ (0.3)	2.3	$ 1.2
Commercial and other
Variable Interest Entity
Securitized assets	28,700.0		28,700.0		28,800.0
Liquidation losses	0.0	0.0	0.0	0.0
Mortgage securitizations - Non-agency-sponsored
Variable Interest Entity
Securitized assets	58,700.0		58,700.0		59,600.0
Liquidation losses	0.0	$ (0.3)	2.3	$ 1.2
Personal loan
Variable Interest Entity
Securitized assets	100.0		100.0
90+ days past due | Residential mortgages
Variable Interest Entity
Securitized assets	500.0		500.0		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	$ 500.0		$ 500.0		$ 500.0