Preferred Stock and Common Stock -Schedule of Number of Shares of Common Stock Reserved for Future Issuance (Details) - shares	Jun. 30, 2020	Dec. 31, 2019
Class Of Stock [Line Items]
Number of shares of common stock reserved for future issuance	5,982,476	4,162,361
Options Issued and Outstanding
Class Of Stock [Line Items]
Number of shares of common stock reserved for future issuance	2,140,012	2,562,800
Restricted stock units
Class Of Stock [Line Items]
Number of shares of common stock reserved for future issuance	661,778	828,935
Options Available for Future Grants
Class Of Stock [Line Items]
Number of shares of common stock reserved for future issuance	2,260,656	215,043
Shares Available for Issuance under the 2018 ESPP
Class Of Stock [Line Items]
Number of shares of common stock reserved for future issuance	920,030	555,583