SECURITIZATIONS AND VARIABLE INTEREST ENTITIES - Loan Delinquencies and Liquidation Losses (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Residential mortgages
Variable Interest Entity
Securitized assets	$ 29,300.0		$ 29,300.0		$ 29,200.0
Liquidation losses	(0.3)	$ 5.0	1.2	$ 6.6
Commercial and other
Variable Interest Entity
Securitized assets	21,700.0		21,700.0		26,200.0
Liquidation losses	0.0	0.0	0.0	0.0
Mortgage securitizations - Non-agency-sponsored
Variable Interest Entity
Securitized assets	51,000.0		51,000.0		55,400.0
Liquidation losses	(0.3)	$ 5.0	1.2	$ 6.6
Personal loan
Variable Interest Entity
Securitized assets	200.0		200.0
90 days or more past due | Residential mortgages
Variable Interest Entity
Securitized assets	500.0		500.0		400.0
90 days or more past due | Commercial and other
Variable Interest Entity
Securitized assets	0.0		0.0		0.0
90 days or more past due | Mortgage securitizations - Non-agency-sponsored
Variable Interest Entity
Securitized assets	$ 500.0		$ 500.0		$ 400.0