SHARE-BASED COMPENSATION, STOCK OPTIONS, AND RESTRICTED SECURITIES (Details) - USD ($) $ in Thousands			1 Months Ended			12 Months Ended
	Jan. 21, 2021	Aug. 04, 2020	Jan. 31, 2019	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2020	Dec. 31, 2019	Jan. 31, 2020	Apr. 30, 2015
Stock options
Expected term						10 years
Aggregate number of shares reserved for issuance						24,718,353
Vesting period						48 months
Stock-based compensation (in dollars)						$ 215	$ 268
Stock Options
Stock options
Granted (in shares)						0	3,000
Aggregate number of shares reserved for issuance						4,169
Stock-based compensation (in dollars)						$ 117	$ 165
RSU
Stock options
Aggregate number of shares reserved for issuance						100
Vesting period						3 years
Stock-based compensation (in dollars)						$ 98	$ 103
Common Stock
Stock options
Stock issued under ESPP (in shares)			36				36
2010 Plan
Stock options
Granted (in shares)				0
Expected term						10 years
2015 Plan
Stock options
Shares available for future grants						427,272
Shares authorized for issuance		400,000						26,667	5,333
Expected term						10 years
2015 Plan Amendment
Stock options
Shares authorized for issuance								32,000
Increase in shares of common stock reserved for issuance (in shares)	26,667	400,000
2007 Plan
Stock options
Expected term						10 years
Employee Stock Purchase Plan
Stock options
Shares authorized for issuance					250
Percentage of outstanding shares reserved for future issuance					1.00%
Increase in shares of common stock reserved for issuance (in shares)					67
Aggregate number of shares reserved for issuance						0
Offering Period						6 months
Stock-based compensation (in dollars)						$ 0	$ 0
Employee Stock Purchase Plan | Maximum
Stock options
Aggregate number of shares reserved for issuance					1,667