COMMITMENTS AND CONTINGENCIES - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Loss Contingencies [Line Items]
Estimated liability, representation and warranties	$ 10.2		$ 10.2
Residential mortgage loan repurchase liability	1,300.0		1,300.0
Rent expense, net of sublease income	3.6	$ 3.3	7.0	$ 6.8
Sublease rentals	0.6		0.6
Unfunded Loan Commitment | Consumer Portfolio Segment | Consumer Loan SPVs
Loss Contingencies [Line Items]
Financing receivable	$ 254.9		$ 254.9