Quarterly report pursuant to Section 13 or 15(d)

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

v2.4.0.6
Stock-Based Compensation and Employee Benefit Plans - Fair Value of Employee Stock Purchase Rights (Detail) (Employee Stock Purchase Rights [Member], USD $)
9 Months Ended
Sep. 30, 2012
Sep. 30, 2011
Employee Stock Purchase Rights [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Weighted-average grant date fair value per share $ 1.28 $ 2.46
Risk-free interest rate 0.15% 0.07%
Dividend yield      
Expected life (years) 6 months 6 months
Volatility 46.60% 45.70%