STOCKHOLDERS' EQUITY - Warrants (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Net proceeds from issuance of Series A Preferred Warrants	$ 385	$ 73	$ 127
Registration statement
Class of Stock [Line Items]
Warrant right to purchase a share of common stock (in shares)	0.25
Premium of the exercise price of the warrant as a percent to net asset value of common stock	15.00%
Series A Preferred Unit
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)	4,484,376
Net proceeds from issuance of Series A Preferred Warrants	$ 586