SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - EPS Two-class Method (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net loss attributable to common stockholders	$ (6,341)	$ (2,585)	$ (16,811)	$ (4,120)
Undistributed net loss attributable to common stockholders	(6,341)	(3,309)	(16,811)	(6,050)
Class A
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net loss attributable to common stockholders	(3,763)	(1,537)	(9,978)	(2,451)
Less: Common Stock cash distributions declared	0	430	0	1,148
Undistributed net loss attributable to common stockholders	$ (3,763)	$ (1,967)	$ (9,978)	$ (3,599)
Net loss per common share, basic and diluted (in dollars per share)	$ (0.21)	$ (0.09)	$ (0.56)	$ (0.14)
Weighted-average number of common shares outstanding, basic and diluted (in shares)	17,842,289	17,930,156	17,860,958	17,955,331
Class T
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net loss attributable to common stockholders	$ (2,578)	$ (1,048)	$ (6,833)	$ (1,669)
Less: Common Stock cash distributions declared	0	294	0	782
Undistributed net loss attributable to common stockholders	$ (2,578)	$ (1,342)	$ (6,833)	$ (2,451)
Net loss per common share, basic and diluted (in dollars per share)	$ (0.21)	$ (0.09)	$ (0.56)	$ (0.14)
Weighted-average number of common shares outstanding, basic and diluted (in shares)	12,222,534	12,230,499	12,231,843	12,221,952