Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation - Weighted-Average Assumptions Used to Estimate Fair Value of Options Granted (Detail)

v3.5.0.2
Stock-Based Compensation - Weighted-Average Assumptions Used to Estimate Fair Value of Options Granted (Detail) - $ / shares
3 Months Ended 6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Jun. 30, 2016
Jun. 30, 2015
Stock options        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Volatility   58.83%   63.89%
Risk free interest rate   1.61%   1.65%
Dividend yield   0.00%   0.00%
Term (years)   5 years 11 months 27 days   6 years 1 month 24 days
Weighted-average fair value of options granted during the period   $ 5.71   $ 5.77
Non-Employee        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Volatility 74.61% 69.85% 75.26% 70.18%
Risk free interest rate 1.27% 2.42% 1.42% 2.15%
Dividend yield 0.00% 0.00% 0.00% 0.00%
Term (years) 7 years 10 months 21 days 8 years 10 months 2 days 8 years 7 days 8 years 11 months 16 days