MORTGAGE LOANS, NET - Loans by Expected End-Use (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) Loan	Dec. 31, 2018 USD ($) Loan	Dec. 31, 2017 USD ($)
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Principal Amount	$ 12,682	$ 36,297
Less: valuation allowance	(12,682)	(13,063)	$ (12,682)
Net Carrying Amount	$ 0	$ 23,234	$ 19,668
Loan Percentage	100.00%	100.00%
Number of Loans | Loan	2	6
Residential
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Principal Amount	$ 12,682	$ 13,063
Loan Percentage	100.00%	36.00%
Number of Loans | Loan	2	3
Commercial
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Principal Amount	$ 0	$ 23,234
Loan Percentage	0.00%	64.00%
Number of Loans | Loan	0	3