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Stock-Based Compensation and Employee Stock Purchase Program - Weighted-Average Fair Value Assumption of Stock Option Awards (Detail) - Employee Stock Option [Member]
3 Months Ended 6 Months Ended
Jun. 30, 2022
Jun. 30, 2021
Jun. 30, 2022
Jun. 30, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Expected term (years) 6 years 10 months 6 days 6 years 10 months 2 days 6 years 7 months 9 days 6 years 4 months 13 days
Expected volatility 123.00% 122.00% 122.00% 122.00%
Risk-free interest rate 2.85% 1.06% 2.48% 0.81%