Convertible Preferred Stock and Stockholders' Deficit - Summary of Plan Activity for Shares Issued and Outstanding and Number of Shares Remaining Available for Grant (Details) - 2018 Equity Incentive Plan - shares	6 Months Ended
	Jun. 30, 2020	Sep. 17, 2018
Class Of Stock [Line Items]
Common stock granted under the 2018 Equity Incentive Plan	6,658,878
Common stock available for grant under the 2018 Equity Incentive Plan	375,093
Number of shares remaining available for grant	7,033,971	7,033,971