Summary of Significant Accounting Policies - Reconciliation of Basic and Diluted Income (Loss) per Share (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021		Dec. 31, 2020
Numerator:
Net loss	$ (2,631)	$ (1,140)	$ (2,473)	$ (1,642)	$ 65	$ (1,165)	$ (4,340)	$ (541)	$ (7,886)		$ (5,981)
Denominator:
Basic (in shares)	5,312	5,086	4,211	3,612	3,491	3,308	3,192	3,086	4,561	[1]	3,270	[1]
Diluted (in shares)	5,312	5,086	4,211	3,612	4,307	3,308	3,192	3,086	4,561	[1]	3,270	[1]

[1]       *Shares outstanding for prior periods have been restated for the 1-for-5 reverse stock split effective June 11, 2020.