REDEEMABLE PREFERRED STOCK - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Class of Stock [Line Items]
Gross proceeds from issuance of preferred stock and warrants	$ 163,700,000
Net proceeds from issuance of preferred stock	5,465,000	$ 8,643,000
Issuance offering costs for preferred stock and warrants	13,500,000
Non-issuance offering costs for preferred stock and warrants	$ 7,500,000
Series A Preferred Warrants
Class of Stock [Line Items]
Warrants issued (in shares)	4,603,287
Gross proceeds from issuance of preferred stock and warrants	$ 761,000
Issuance offering costs for preferred stock and warrants	142,000
Reclassification to deferred rent receivable and charges	$ 5,000
Warrants outstanding (in shares)	4,603,287
Series A Preferred Stock
Class of Stock [Line Items]
Gross proceeds from issuance of preferred stock and warrants	$ 162,400,000
Issuance offering costs for preferred stock and warrants	13,400,000
Reclassification to deferred rent receivable and charges	$ 1,400,000
Preferred stock, shares outstanding (in shares)	6,688,077
Preferred stock, shares redeemed (in shares)	136,476
Series A Preferred Stock | Preferred Stock, Shares Issued, One
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)	6,526,081
Series A Preferred Stock | Preferred Stock, Shares Issued, Two
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)	298,472
Net proceeds from issuance of preferred stock	$ 0
Series D Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)	23,190		19,145
Gross proceeds from issuance of preferred stock and warrants	$ 572,000
Net proceeds from issuance of preferred stock		$ 0
Issuance offering costs for preferred stock and warrants	18,000
Reclassification to deferred rent receivable and charges	$ 5,000
Preferred stock, shares outstanding (in shares)	23,190	0	19,145
Preferred stock, shares redeemed (in shares)	0
Series A Preferred Unit
Class of Stock [Line Items]
Number of securities called by warrants or rights (in shares)	1,194,159