Net Loss Per Share - Computation of Basic and Diluted Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Numerator:
Net loss	$ (3,433)	$ (3,129)
Less: preferred stock dividends	(1)	(4)
Less: undeclared dividends	(366)	0
Induced conversion of Series A-2 Preferred Stock	(300)	0
Net loss attributable to common stockholders	$ (4,100)	$ (3,133)
Denominator:
Weighted-average number of shares of common stock for diluted net loss per share (in shares)	17,756	5,204
Basic and diluted net loss per share (in dollars per share)	$ (0.23)	$ (0.60)