Basis of Presentation - Summary of Potentially Dilutive Securities Not Included in Calculation of Diluted Net Loss Per Share (Details) - shares	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total	3,403,587	18,590,315
Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total		16,685,014
Preferred Stock Warrant
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total		23,122
Common Stock Warrant
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total	23,122
Common Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total	3,332,545	1,684,630
Unvested Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total	47,920	197,549