Calculations for Basic Net Loss Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Numerator:
Net loss	$ (1,465)	$ (2,047)
Accretion of Series B convertible preferred stock dividends	(284)	(270)
Numerator for basic net loss per share - net loss available to common stockholders	$ (1,749)	$ (2,317)
Denominator:
Weighted average common shares outstanding - basic	18,443	17,521
Net loss per common share - basic	$ (0.09)	$ (0.13)