Equity Incentive Plans - Summary of Estimated Fair Value of Shares Under Employee Stock Purchase Plan (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Fair Value Assumptions
Expected volatility, Minimum	93.00%	80.20%	81.20%	78.40%
Expected volatility, Maximum	93.50%	80.40%	93.50%	80.40%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Risk-free interest rate	0.30%
Minimum
Fair Value Assumptions
Expected term (in years)	5 years 7 months 6 days	6 years	5 years 7 months 6 days	5 years 10 months 24 days
Maximum
Fair Value Assumptions
Expected term (in years)	5 years 7 months 6 days	6 years 1 month 6 days	6 years 1 month 6 days	6 years 1 month 6 days
2020 Employee Stock Purchase Plan
Fair Value Assumptions
Expected volatility, Minimum	109.70%		107.00%
Expected volatility, Maximum	158.20%		158.20%
Expected dividend yield	0.00%		0.00%
Risk-free interest rate	0.20%		0.20%
2020 Employee Stock Purchase Plan | Minimum
Fair Value Assumptions
Expected term (in years)	4 months 24 days		4 months 24 days
2020 Employee Stock Purchase Plan | Maximum
Fair Value Assumptions
Expected term (in years)	1 year 10 months 24 days		1 year 10 months 24 days