PREFERRED STOCK AND STOCKHOLDERS’ DEFICIT - Carrying Value of Series A and C Preferred Stock (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Dividends		$ 300
Accretion of discount		100
Convertible Preferred Stock
Class of Stock [Line Items]
Preferred dividend yield	11.50%
Series A Preferred Stock
Class of Stock [Line Items]
Dividends	$ 300
Accretion of discount	100
Increase (Decrease) in Temporary Equity [Roll Forward]
Preferred stock carrying value, beginning of period	2,827	2,462
Dividends and discount accretion	404	365
Preferred stock carrying value, at end of period	3,231	2,827
Series C Preferred Stock
Class of Stock [Line Items]
Dividends	10,100	9,100
Accretion of discount	700	600
Increase (Decrease) in Temporary Equity [Roll Forward]
Preferred stock carrying value, beginning of period	79,252	69,540
Dividends and discount accretion	10,806	9,712
Preferred stock carrying value, at end of period	$ 90,058	$ 79,252