LOANS - Geographic Concentrations Based on Unpaid Principal Balances (Details) - Residential mortgage loans - Geographic Concentration Risk	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
All Locations
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Geographic Concentrations of Residential Mortgage Loans	100.00%	100.00%
California
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Geographic Concentrations of Residential Mortgage Loans	37.50%	40.10%
New York
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Geographic Concentrations of Residential Mortgage Loans	10.60%	10.50%
Florida
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Geographic Concentrations of Residential Mortgage Loans	10.50%	10.60%
Texas
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Geographic Concentrations of Residential Mortgage Loans	5.60%	5.60%
All other (none individually greater than 5%)
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Geographic Concentrations of Residential Mortgage Loans	35.80%	33.20%