Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Condensed Balance Sheets [Abstract]
Trade receivables, allowance for doubtful accounts	$ 11	$ 11
Common stock, par value	$ 0.10	$ 0.10
Common stock, shares authorized	10,000,000	10,000,000
Common stock, shares issued	3,395,521	3,395,521
Common stock, shares outstanding	3,395,521	3,395,521