REAL ESTATE HELD FOR INVESTMENT - Operating Leases, Additional Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($) tenant	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)
Operating Leased Assets [Line Items]
Recognition of deferred revenue, net of discontinued operations	$ 1,000	$ 1,300
Deferred rent receivables	14,900		$ 13,600
Incentive to lessee	$ 3,300		3,100
Number of tenants | tenant	243
Adjustments to rental income	$ 200	$ 100
Prepaid expenses and other assets (Other liabilities)
Operating Leased Assets [Line Items]
Security deposit liability	$ 4,300		$ 4,300
Maximum
Operating Leased Assets [Line Items]
Operating lease, term	12 years
Weighted Average
Operating Leased Assets [Line Items]
Operating lease, term	4 years 4 months 24 days
Apartment Building
Operating Leased Assets [Line Items]
Operating lease, term	1 year