Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
ASSETS
Other physical property, accumulated depreciation	$ 483	$ 458
CURRENT ASSETS:
Accounts receivables, reserves	$ 855	$ 655
COMMON STOCKHOLDERS' EQUITY:
Common stock, par value (in dollars per share)	$ 0	$ 0
Common stock, authorized (in shares)	46,500,000	46,500,000
Common stock, issued (in shares)	13,112,948	13,060,817
Common stock, outstanding (in shares)	13,112,948	13,060,817
Preferred stock, authorized (in shares)	500,000	500,000
Preferred stock, issued (in shares)	0	0