Stockholders' Equity (Details) - shares	Sep. 30, 2021	Dec. 31, 2020
Common Stock
Total number of shares reserved for issuance (in shares)	10,891,288	9,500,287
Shares of common stock subject to outstanding options
Common Stock
Options issued and outstanding (in shares)	4,961,248	4,867,303
Shares available for issuance (in shares)	4,439,910	3,061,589
Employee stock purchase plan
Common Stock
Shares available for issuance (in shares)	1,490,130	1,571,395