Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation and Employee Benefit Plans Stock-Based Compensation and Employee Benefit Plans - Fair Value of Employee Stock Purchase Rights (Details)

v2.4.0.8
Stock-Based Compensation and Employee Benefit Plans Stock-Based Compensation and Employee Benefit Plans - Fair Value of Employee Stock Purchase Rights (Details) (Employee Stock Purchase Rights [Member], USD $)
6 Months Ended
Jun. 30, 2014
Jun. 30, 2013
Employee Stock Purchase Rights [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Weighted-average grant date fair value per share $ 2.47 $ 1.85
Risk-free interest rate 0.05% 0.09%
Dividend yield 0.00% 0.00%
Expected life (years) 0 years 182 days 0 years 182 days
Volatility 47.75% 41.58%