CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accounts receivable, allowances	$ 178	$ 299
Debt instrument debt issuance costs, current	$ 59	$ 41
Preferred stock, par value	$ 0.001
Preferred stock, shares authorized	10,000,000
Preferred stock, outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	19,450,000	18,209,000
Common stock, shares outstanding	18,055,000	16,986,000
Treasury stock, shares	1,395,000	1,223,000
Series B Convertible Preferred Stock
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, issued	5,000,000	5,000,000
Preferred stock, outstanding	5,000,000	5,000,000