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				6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Numerator:
Net loss	$ (2,246)	$ (3,433)	$ (3,385)	$ (3,129)	$ (5,679)	$ (6,514)
Less: preferred stock dividends	0		(4)		(1)	(8)
Less: undeclared dividends	0		0		(366)	0
Induced conversion of Series A-2 Preferred Stock	0		0		(300)	0
Net loss attributable to common stockholders	(2,246)		(3,389)		(6,346)	(6,522)
Net loss attributable to common stockholders	$ (2,246)		$ (3,389)		$ (6,346)	$ (6,522)
Denominator:
Diluted (in shares)	26,644		5,240		22,250	5,222
Basic net loss per share (in dollars per share)	$ (0.08)		$ (0.65)		$ (0.29)	$ (1.25)
Diluted net loss per share (in dollars per share)	$ (0.08)		$ (0.65)		$ (0.29)	$ (1.25)