INVESTMENT IN AN UNCONSOLIDATED ENTITY - Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Balance Sheets [Abstract]
Real estate, net	$ 2,035,127
Cash and cash equivalents	46,653		$ 43,984
Total assets	2,621,478		2,638,927
Notes payable, net	1,497,349		1,459,879
Equity	899,233	$ 870,683	985,310	$ 930,895
Total liabilities and equity	2,621,478		2,638,927
Income Statement [Abstract]
Revenues	77,702	111,378
Expenses:
Real estate taxes and insurance	14,103	17,446
General and administrative expenses	1,677	2,035
Depreciation and amortization	27,392	41,408
Interest expense	48,789	37,947
Total expenses	135,288	138,149
Other income	0	13
Equity in loss of an unconsolidated entity	(1,161)	0
Operating, maintenance and management
Expenses:
Expenses	18,257	23,735
Asset management fees
Expenses:
Expenses	5,174	$ 6,872
SREIT
Balance Sheets [Abstract]
Real estate, net	1,361,969		1,201,050
Cash and cash equivalents	17,140		37,862
Other assets	27,051		21,628
Total assets	1,406,160		1,260,540
Notes payable, net	483,159		432,824
Accounts payable and other liabilities	66,971		40,716
Equity	856,030		787,000
Total liabilities and equity	1,406,160		$ 1,260,540
Income Statement [Abstract]
Revenues	35,462
Expenses:
Real estate taxes and insurance	4,678
General and administrative expenses	605
Depreciation and amortization	15,483
Interest expense	18,016
Total expenses	47,397
Other income	3
Net loss	(11,932)
Equity in loss of an unconsolidated entity	(3,257)
SREIT | Purchase and Sales Agreement
Expenses:
Equity in loss of an unconsolidated entity	(1,200)
Equity in gain for dilution of an unconsolidated entity	2,100
SREIT | Operating, maintenance and management
Expenses:
Expenses	6,819
SREIT | Asset management fees
Expenses:
Expenses	$ 1,796