Stock-Based Compensation - Accounting for Stock-based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation	$ 562	$ 404	$ 1,107	$ 1,515
Research and development
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation	61	53	156	433
Research and development | Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation	9	3	15	15
Research and development | Equity Incentive Plans
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation	52	50	141	418
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation	501	351	951	1,082
General and administrative | Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation	1	1	3	3
General and administrative | Equity Incentive Plans
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation	$ 500	$ 350	$ 948	$ 1,079