Net Loss Per Share - Reconciliation of Basic and Diluted Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Numerator:
Net loss	$ (7,421)	$ (9,051)	$ (7,421)
Less: preferred stock dividends		1	17
Less: undeclared dividends		366	788
Less: conversion inducement		300	0
Less: warrant modification		37	0
Net loss attributable to common stockholders		$ (9,755)	$ (8,226)
Denominator:
Weighted-average number of shares of common stock for diluted net loss per share (in shares)		26,567	5,547
Basic net loss per share (in dollars per share)		$ (0.37)	$ (1.48)
Diluted net loss per share (in dollars per share)		$ (0.37)	$ (1.48)