Stock Plans (Details 2)
3 Months Ended 6 Months Ended
Jun. 30, 2012
Jun. 30, 2011
Jun. 30, 2012
Jun. 30, 2011
Weighted Average Assumptions for fair value of stock options granted to employees        
Dividend rate 0.00% 0.00% 0.00% 0.00%
Risk-free interest rate 0.90% 1.90% 1.10% 2.50%
Expected term (in years) 5 years 9 months 18 days 5 years 2 months 12 days 6 years 6 years 1 month 6 days
Expected volatility 47.00% 48.00% 49.00% 48.00%
ESPP [Member]
       
Weighted Average Assumptions for fair value of stock options granted to employees        
Dividend rate 0.00%    0.00%   
Risk-free interest rate 0.20%    0.20%   
Expected term (in years) 6 months    6 months   
Expected volatility 38.00%    38.00%