Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation - Schedule of Weighted-Average Assumptions Used for Calculating Value of Options Granted (Detail)

v3.3.0.814
Stock-Based Compensation - Schedule of Weighted-Average Assumptions Used for Calculating Value of Options Granted (Detail)
3 Months Ended 9 Months Ended
Sep. 30, 2015
Sep. 30, 2014
Sep. 30, 2015
Sep. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options Outstanding, Weighted Average Exercise Price, and Additional Disclosures [Abstract]        
Dividend yield 0.00% 0.00% 0.00% 0.00%
Expected volatility 72.65%   72.65%  
Expected volatility 73.43%   75.07%  
Risk-free interest rate 1.69%   1.49%  
Risk-free interest rate 1.89%   1.89%  
Forfeiture rate 8.80%   8.80%  
Minimum [Member]        
Share-based Compensation Arrangement by Share-based Payment Award, Options Outstanding, Weighted Average Exercise Price, and Additional Disclosures [Abstract]        
Expected term 5 years   5 years  
Maximum [Member]        
Share-based Compensation Arrangement by Share-based Payment Award, Options Outstanding, Weighted Average Exercise Price, and Additional Disclosures [Abstract]        
Expected term   6 years 1 month 6 days   6 years 1 month 6 days