Balance Sheet Components - Schedule of Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Payables And Accruals [Abstract]
Accrued employee compensation	$ 20,713	$ 10,885
Accrued research and development costs	3,839	3,057
Accrued asset purchases	3,451	2,527
Accrued professional services	1,819	1,325
Other	3,195	2,148
Total accrued liabilities	$ 33,017	$ 19,942