Equity Incentive Plans - Summary of Estimated Fair Value of Employee Stock Options (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Fair Value Assumptions
Expected volatility, Minimum	86.80%	78.40%	81.20%	78.40%
Expected volatility, Maximum	89.00%	78.50%	89.00%	79.20%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Risk-free interest rate	0.40%	2.40%		2.40%
Risk-free interest rate, Minimum			0.40%
Risk-free interest rate, Maximum			1.40%
Minimum
Fair Value Assumptions
Expected term (in years)	5 years 9 months 18 days	5 years 10 months 24 days	5 years 9 months 18 days	5 years 10 months 24 days
Maximum
Fair Value Assumptions
Expected term (in years)	6 years 1 month 6 days	6 years 1 month 6 days	6 years 1 month 6 days	6 years 1 month 6 days