SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Net Loss Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Net loss attributable to common shareholders
Net loss from continuing operations	$ (13,143)	$ (6,027)	$ (14,077)	$ (12,954)
Net income from discontinued operations	0	7	0	42
Net loss attributable to common shareholders	$ (13,143)	$ (6,020)	$ (14,077)	$ (12,912)
Weighted-average common shares outstanding:
Weighted-average common shares outstanding: basic	63,013,291	61,321,424	62,172,031	61,321,424
Weighted-average common shares outstanding: diluted	63,013,291	61,321,424	62,172,031	61,321,424
Loss per common share – Basic and diluted
Loss from continuing operations, per basic share (in usd per share)	$ (0.21)	$ (0.10)	$ (0.23)	$ (0.21)
Loss from continuing operations, per diluted share (in usd per share)	(0.21)	(0.10)	(0.23)	(0.21)
Loss from discontinued operations, per basic (in usd per share)	0	0	0	0
Loss from discontinued operations, per diluted (in usd per share)	0	0	0	0
Net loss per common share - basic (in usd per share)	(0.21)	(0.10)	(0.23)	(0.21)
Net loss per common share - diluted (in usd per share)	$ (0.21)	$ (0.10)	$ (0.23)	$ (0.21)