STOCK-BASED COMPENSATION EXPENSE - Share-based Compensation, Stock Options, Activity (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Number of Options
Outstanding beginning balance (in shares)	417,000	450,000	613,000	417,000	450,000	613,000
Granted (in shares)	10,000	18,000
Exercised (in shares)	0	(16,000)
Forfeited (in shares)	(43,000)	(165,000)
Outstanding ending balance (in shares)	417,000	450,000	613,000
Number of Options, Exercisable (in shares)				405,000	425,000
Weighted Average Exercise Price
Weighted Average Exercise Price, Beginning balance (in dollars per share)	$ 2.78	$ 2.85
Weighted Average Exercise Price, Granted (in dollars per share)	1.88	2.87
Weighted Average Exercise Price, Exercised (in dollars per share)		2.59
Weighted Average Exercise Price, Forfeited (in dollars per share)	2.54	3.07
Weighted Average Exercise Price, Ending balance (in dollars per share)	$ 2.79	$ 2.78	$ 2.85
Weighted Average Exercise Price, Exercisable (in dollars per share)				$ 2.80	$ 2.79
Weighted Average Remaining Contractual Term (Years)
Weighted Average Remaining Contractual Term (Years)	1 year 7 months 9 days	2 years 5 months 8 days	3 years 1 month 20 days
Weighted Average Remaining Contractual Term (Years) Granted	7 years	7 years
Weighted Average Remaining Contractual Term (Years), Exercisable	1 year 5 months 23 days	2 years 3 months
Aggregate Intrinsic Value
Aggregate Intrinsic Value, Balance				$ 2,000	$ 27,000	$ 0
Aggregate Intrinsic Value, Exercisable				$ 0	$ 0