COMMERCIAL MORTGAGE LOANS HELD-FOR-INVESTMENT Summary of Concentration of Credit Risk (Details) - Commercial loans held-for-investment - Commercial real estate portfolio segment	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Geography
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk (as a percentage)	100.00%	100.00%
Collateral Property Type
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk (as a percentage)	100.00%	100.00%
Multifamily | Collateral Property Type
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk (as a percentage)	89.60%	92.00%
Healthcare | Collateral Property Type
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk (as a percentage)	6.40%	0.00%
Self-Storage | Collateral Property Type
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk (as a percentage)	1.80%	5.20%
Retail | Collateral Property Type
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk (as a percentage)	1.60%	1.70%
Office | Collateral Property Type
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk (as a percentage)	0.60%	1.10%
South | Geography
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk (as a percentage)	46.60%	46.20%
Southwest | Geography
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk (as a percentage)	26.70%	27.50%
West | Geography
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk (as a percentage)	6.30%	13.90%
Mid-Atlantic | Geography
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk (as a percentage)	12.40%	7.90%
Midwest | Geography
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk (as a percentage)	8.00%	4.50%