Equity Plans and Stock-Based Compensation - Fair Value-Based Measurements and Weighted-Average Assumptions (Detail) - $ / shares |
3 Months Ended | 6 Months Ended | ||
---|---|---|---|---|
Jun. 30, 2020 |
Jun. 30, 2019 |
Jun. 30, 2020 |
Jun. 30, 2019 |
|
Stock Options | ||||
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | ||||
Weighted-average fair value per share | $ 3.77 | $ 4.92 | $ 3.61 | $ 4.67 |
Risk-free interest rate | 0.30% | 2.30% | 1.20% | 2.20% |
Expected life (in years) | 4 years 6 months | 4 years 6 months | 4 years 6 months | 4 years 6 months |
Volatility | 0.90% | 0.90% | 0.90% | 0.90% |
Employee Stock Purchase Plan | ||||
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | ||||
Weighted-average fair value per share | $ 2.17 | $ 5.19 | ||
Risk-free interest rate | 1.50% | 2.50% | ||
Expected life (in years) | 1 year 2 months 12 days | 1 year 2 months 12 days | ||
Volatility | 0.60% | 0.80% |