Quarterly report pursuant to Section 13 or 15(d)

Stock-based Compensation Plans and Awards (Fair Value Assumptions for Options) (Details)

v2.4.0.8
Stock-based Compensation Plans and Awards (Fair Value Assumptions for Options) (Details) (Black Scholes Options Pricing Model)
3 Months Ended 9 Months Ended
Sep. 30, 2014
Sep. 30, 2013
Sep. 30, 2014
Sep. 30, 2013
Employee Stock
       
Assumptions used to calculate per-share fair value of award        
Expected life 6 months   6 months  
Expected volatility 42.00%   42.00%  
Expected dividend yield (as a percent) 0.00%   0.00%  
Employee Stock | Minimum
       
Assumptions used to calculate per-share fair value of award        
Risk-free interest rate (as a percent) 0.05%   0.05%  
Employee Stock | Maximum
       
Assumptions used to calculate per-share fair value of award        
Risk-free interest rate (as a percent) 0.08%   0.08%  
Options to purchase common stock
       
Assumptions used to calculate per-share fair value of award        
Expected life 6 years 29 days 6 years 3 months 26 days 6 years 29 days  
Risk-free interest rate (as a percent) 1.93% 2.04%    
Expected volatility 58.00% 58.00%    
Expected dividend yield (as a percent) 0.00% 0.00% 0.00% 0.00%
Options to purchase common stock | Minimum
       
Assumptions used to calculate per-share fair value of award        
Expected life       5 years 11 months 27 days
Risk-free interest rate (as a percent)     1.71% 0.99%
Expected volatility     58.00% 57.00%
Options to purchase common stock | Maximum
       
Assumptions used to calculate per-share fair value of award        
Expected life       6 years 3 months 26 days
Risk-free interest rate (as a percent)     1.93% 2.04%
Expected volatility     59.00% 59.00%