XML 50 R40.htm IDEA: XBRL DOCUMENT v3.7.0.1
Stock-Based Compensation - Estimated Fair Values of Employee Stock Options Granted (Detail) - Employee Stock Option [Member]
3 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected option life (years)   6 years 2 months 16 days
Expected volatility   70.00%
Expected dividend yield 0.00% 0.00%
Minimum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected option life (years) 5 years 9 months 18 days  
Risk-free interest rate 2.10% 1.61%
Expected volatility 76.60%  
Maximum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected option life (years) 6 years 8 months 16 days  
Risk-free interest rate 2.23% 1.94%
Expected volatility 79.90%