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Stockholders Equity (Details)
3 Months Ended 6 Months Ended
Jun. 30, 2012
Jun. 30, 2011
Jun. 30, 2012
Jun. 30, 2011
Stock Option [Member]
       
Stock-based compensation expense        
Expected dividend yield 0.00% 0.00% 0.00% 0.00%
Expected volatility 72.00% 66.00% 73.00% 66.00%
Expected life (in years) 6 years 0 months 6 years 0 months 6 years 0 months 6 years 0 months
Risk free interest rate, Minimum 0.90%      
Risk free interest rate   2.20%    
Stock Option [Member] | Maximum [Member]
       
Stock-based compensation expense        
Risk free interest rate, Maximum     1.10% 2.50%
Stock Option [Member] | Minimum [Member]
       
Stock-based compensation expense        
Risk free interest rate, Minimum     0.90% 2.20%
ESPP [Member]
       
Stock-based compensation expense        
Expected dividend yield 0.00% 0.00% 0.00% 0.00%
ESPP [Member] | Maximum [Member]
       
Stock-based compensation expense        
Expected volatility 72.00% 58.00% 74.00% 58.00%
Expected life (in years) 1 year 1 year 1 year 1 year
Risk free interest rate, Maximum 0.20% 0.40% 0.20% 0.40%
ESPP [Member] | Minimum [Member]
       
Stock-based compensation expense        
Expected volatility 65.00% 55.00% 58.00% 55.00%
Expected life (in years) 6 months 6 months 6 months 6 months
Risk free interest rate, Minimum 0.20% 0.10% 0.10% 0.10%