Quarterly report pursuant to Section 13 or 15(d)

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 Fair Value of Employee Stock Purchase Rights (Details) (Employee Stock Purchase Rights [Member], USD $)
9 Months Ended
Sep. 30, 2013
Sep. 30, 2012
Employee Stock Purchase Rights [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Weighted-average grant date fair value per share (usd per share) $ 1.85 $ 1.28
Risk-free interest rate 0.09% 0.15%
Dividend yield 0.00% 0.00%
Expected life (years) 6 months 6 months
Volatility 41.58% 46.60%