Balance Sheet Components - Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued compensation	$ 3,886	$ 4,277
External research and development	5,821	7,694
Accrued outside services	807	945
Accrued taxes	133	40
Accrued restructuring costs	18	0
Other accrued expenses	266	7
Total accrued expenses	$ 10,931	$ 12,963