Quarterly report pursuant to Section 13 or 15(d)

Stock Option and Incentive Plans - Assumptions to Compute Fair Value of Stock Option Grants (Detail)

v3.19.2
Stock Option and Incentive Plans - Assumptions to Compute Fair Value of Stock Option Grants (Detail) - USD ($)
3 Months Ended 6 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Jun. 30, 2019
Jun. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]        
Risk free interest rate 2.28% 2.81% 2.37% 2.57%
Expected dividend yield $ 0   $ 0  
Expected term (in years) 6 years 1 month 2 days 5 years 4 months 24 days 6 years 29 days 6 years 7 days
Expected volatility 90.00% 82.50% 89.70% 82.30%