Equity Incentive Plans - Summary of Estimated Fair Value of Employee Stock Options (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%
Risk-free interest rate, Minimum		1.60%	0.30%	1.60%
Risk-free interest rate, Maximum		1.80%	1.40%	2.40%
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