Stockholders' Equity - Summary of Assumptions Used to Determine Fair Value of Employee Stock Option Grants, Employee Stock Purchase Plan and Performance Options with Market Condition (Detail)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
ESPP [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 months	6 months	6 months
Risk-free interest rate, minimum	0.04%	0.10%	1.60%
Risk-free interest rate, maximum	0.12%	1.60%	2.50%
Expected volatility, minimum	89.70%	89.70%	99.70%
Expected volatility, maximum	108.12%	143.20%	141.70%
Expected dividend yield	0.00%	0.00%	0.00%
Employee Stock Option [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate, minimum	0.60%	0.30%	1.40%
Risk-free interest rate, maximum	1.30%	1.50%	2.60%
Expected volatility, minimum	86.30%	102.20%	97.20%
Expected volatility, maximum	104.80%	109.70%	105.40%
Expected dividend yield	0.00%	0.00%	0.00%
Employee Stock Option [Member] | Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	5 years 6 months	5 years 6 months	5 years 6 months 3 days
Employee Stock Option [Member] | Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 years 29 days	6 years 29 days	6 years 25 days