Quarterly report pursuant to Section 13 or 15(d)

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

v3.10.0.1
Stock Option and Incentive Plans - Assumptions to Compute Fair Value of Stock Option Grants (Detail) - USD ($)
3 Months Ended 9 Months Ended
Sep. 30, 2018
Sep. 30, 2018
Sep. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]      
Risk free interest rate 0.00% 2.57% 2.08%
Expected dividend yield $ 0 $ 0  
Expected term (in years)   6 years 7 days 6 years
Expected volatility 0.00% 82.30% 79.10%