RELATED PARTY TRANSACTIONS - Investment in Pacific Oak Opportunity Zone Fund I (Details) - Pacific Oak Opportunity Zone Fund I $ in Thousands	3 Months Ended
	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($) unit	Dec. 31, 2019 USD ($) unit
Schedule of Equity Method Investments [Line Items]
Number of units in real estate property | unit		7	91
Investments			$ 20,600
Investments, fair value		$ 1,500
Acquisition fee, percent of purchase price fee	1.50%
Investment, purchase price, benchmark	$ 25,000
Acquisition fee of purchase price fee in excess of benchmark purchase price	1.00%
Asset management fee, percent	0.25%
Financing fee as percent of original principal amount of any indebtedness	0.50%
Waived asset management fees	$ 200
Asset management fees receivable	$ 400
POSOR II Merger
Schedule of Equity Method Investments [Line Items]
Number of units in real estate property | unit		13
Investments		$ 2,900
Investments, fair value		$ 3,000