INVESTMENT IN AN UNCONSOLIDATED ENTITY - Additional Information (Details) $ / shares in Units, $ in Thousands			3 Months Ended		6 Months Ended
	Jul. 19, 2019 USD ($) $ / shares shares	Jul. 18, 2019 property	Jun. 30, 2021 USD ($) $ / shares shares	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($) $ / shares shares	Jun. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)	Aug. 21, 2019 USD ($) shares
Schedule of Equity Method Investments [Line Items]
Investment in an unconsolidated entity			$ 227,038		$ 227,038		$ 233,592
Equity in income (loss) of an unconsolidated entity			63	$ (835)	3,350	$ (1,996)
SREIT
Schedule of Equity Method Investments [Line Items]
Equity in income (loss) of an unconsolidated entity			63	$ (835)	3,350	(4,092)
Purchase and Sales Agreement | SREIT
Schedule of Equity Method Investments [Line Items]
Investment in an unconsolidated entity			$ 227,000		227,000
Equity in gain for dilution of an unconsolidated entity						2,100
Investment income, dividends					$ 9,900	$ 11,900
REIT Properties III
Schedule of Equity Method Investments [Line Items]
Units value (in dollars per unit) | $ / shares			$ 0.87		$ 0.87
Ownership percentage			27.30%		27.30%			31.30%
Units disposed (in units) | shares								18,392,100
Units disposed								$ 16,200
Units held (in units) | shares			289,561,899		289,561,899
Investment in an unconsolidated entity			$ 250,500		$ 250,500
REIT Properties III | Purchase and Sales Agreement
Schedule of Equity Method Investments [Line Items]
Units acquired (in units) | shares	307,953,999
Aggregate cost	$ 271,000
Units value (in dollars per unit) | $ / shares	$ 0.88
Ownership percentage	33.30%
Disposed of by Sale | SREIT
Schedule of Equity Method Investments [Line Items]
Number of real estate properties disposed | property		11