Quarterly report pursuant to Section 13 or 15(d)

Stock-based Compensation Plans and Awards - Schedule of assumptions used for determining the per-share fair value (Details)

v3.3.0.814
Stock-based Compensation Plans and Awards - Schedule of assumptions used for determining the per-share fair value (Details) - Black Scholes Options Pricing Model
3 Months Ended 9 Months Ended
Sep. 30, 2015
Sep. 30, 2014
Sep. 30, 2015
Sep. 30, 2014
Employee stock        
Assumptions used to calculate per-share fair value of award        
Expected life (in years) 6 months 6 months 6 months 6 months
Expected volatility   42.00%   42.00%
Expected dividend yield 0.00% 0.00% 0.00% 0.00%
Employee stock | Minimum        
Assumptions used to calculate per-share fair value of award        
Risk-free interest rate 0.07% 0.05% 0.05% 0.05%
Expected volatility 29.00%   29.00%  
Employee stock | Maximum        
Assumptions used to calculate per-share fair value of award        
Risk-free interest rate 0.24% 0.08% 0.24% 0.08%
Expected volatility 42.00%   42.00%  
Stock options        
Assumptions used to calculate per-share fair value of award        
Expected life (in years) 6 years 29 days 6 years 29 days 6 years 29 days 6 years 29 days
Risk-free interest rate 1.92% 1.93% 1.92%  
Expected volatility 49.00% 58.00% 49.00%  
Expected dividend yield 0.00% 0.00% 0.00% 0.00%
Stock options | Minimum        
Assumptions used to calculate per-share fair value of award        
Risk-free interest rate       1.71%
Expected volatility       58.00%
Stock options | Maximum        
Assumptions used to calculate per-share fair value of award        
Risk-free interest rate       1.93%
Expected volatility       59.00%