Convertible Preferred Stock and Stockholders' Deficit - Schedule of Reserved Shares of Common Stock for Issuance (Details)	Jun. 30, 2020 shares
Class Of Stock [Line Items]
Reserved shares of common stock for issuance	44,091,210
Preferred Stock, as Converted
Class Of Stock [Line Items]
Reserved shares of common stock for issuance	39,859,139
Unvested Restricted Stock Units And Stock Options | 2018 Equity Incentive Plan
Class Of Stock [Line Items]
Reserved shares of common stock for issuance	3,856,978
Stock Available for Grant | 2018 Equity Incentive Plan
Class Of Stock [Line Items]
Reserved shares of common stock for issuance	375,093