Net Loss Per Share - Reconciliation of Basic and Diluted Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Numerator:
Net loss	$ (7,421)	$ (7,761)
Less: preferred stock dividends	17	27
Less: undeclared dividends	788	0
Net loss attributable to common stockholders	$ (8,226)	$ (7,788)
Denominator:
Weighted-average number of shares of common stock for diluted net loss per share (in shares)	5,547	5,108
Basic and diluted net loss per share (in dollars per share)	$ (1.48)	$ (1.52)