Stock-Based Compensation - Schedule of Number of Shares of Common Stock Reserved for Future Issuance (Details) - shares	Sep. 30, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock reserved for future issuance	5,593,764	14,834,849
Stock Options Available for Future Grant
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock reserved for future issuance	2,098,174	653,136
Options Issued and Outstanding
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock reserved for future issuance	3,269,399	1,860,646
Redeemable Convertible Preferred Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock reserved for future issuance		12,048,671
Conversion of Additional Authorized and Unissued Redeemable Convertible Preferred Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock reserved for future issuance		51,506
Redeemable Convertible Preferred Stock Warrant Liability
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock reserved for future issuance		220,890
Common Stock Warrants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock reserved for future issuance	226,191