Quarterly report pursuant to Section 13 or 15(d)

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

v3.5.0.2
Stock Option and Incentive Plans - Assumptions to Compute Fair Value of Stock Option Grants (Detail) - USD ($)
3 Months Ended 9 Months Ended
Sep. 30, 2016
Sep. 30, 2015
Sep. 30, 2016
Sep. 30, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]        
Risk free interest rate 1.37% 1.65% 1.21% 1.60%
Expected dividend yield $ 0 $ 0 $ 0 $ 0
Expected term (in years) 6 years 4 days 6 years 22 days 4 years 11 months 27 days 5 years 8 months 23 days
Expected volatility 76.50% 74.10% 79.50% 73.80%