Net Loss Per Share - Summary of Potentially Dilutive Securities Excluded from Computation of Diluted Weighted-Average Shares Outstanding (Details) - shares	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total number of securities excluded from computation of diluted weighted-average shares outstanding (in shares)	6,626,874	5,967,824
Unvested common stock from early exercise of options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total number of securities excluded from computation of diluted weighted-average shares outstanding (in shares)	36,772	75,043
Stock options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total number of securities excluded from computation of diluted weighted-average shares outstanding (in shares)	6,577,620	5,892,781
Common stock offering from ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total number of securities excluded from computation of diluted weighted-average shares outstanding (in shares)	12,482	0