STOCK-BASED COMPENSATION Summary of ESPP Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Payment Arrangement [Abstract]
Proceeds from common stock issued under ESPP	$ 1,692	$ 397	$ 313
Shares of common stock issued (shares)	315	439	478
Weighted-average price per share (usd per share)	$ 5.37	$ 0.90	$ 0.65

Number of shares issued during the period as a result of an employee stock purchase plan.

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Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration