Quarterly report pursuant to Section 13 or 15(d)

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

v3.19.1
Stock Option and Incentive Plans - Assumptions to Compute Fair Value of Stock Option Grants (Detail) - USD ($)
3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]    
Risk free interest rate 2.51% 2.56%
Expected dividend yield $ 0 $ 0
Expected term (in years) 6 years 21 days 6 years 21 days
Expected volatility 89.30% 82.20%