Stock-Based Compensation - Accounting for Stock-based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation	$ 411	$ 475	$ 1,518	$ 1,990
Research and development
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation	59	58	215	491
Research and development | Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation	6	7	21	22
Research and development | Equity Incentive Plans
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation	53	51	194	469
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation	352	417	1,303	1,499
General and administrative | Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation	2		5	3
General and administrative | Equity Incentive Plans
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation	$ 350	$ 417	$ 1,298	$ 1,496