Quarterly report pursuant to Section 13 or 15(d)

Stock Incentive Plan - Stock Option Grants (Details)

v2.4.0.6
Stock Incentive Plan - Stock Option Grants (Details) (USD $)
 3 Months Ended 6 Months Ended 12 Months Ended 6 Months Ended
Jun. 30, 2012
Jun. 30, 2011
Jun. 30, 2012
Jun. 30, 2011
Jun. 30, 2012
Stock Options [Member]
Dec. 31, 2010
Stock Options [Member]
Jun. 30, 2012
2010 Plan [Member]
Stock Options [Member]
Jun. 30, 2012
2000 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Shares available for grant             9,165,855  
Weighted-average remaining contractual life of all options expected to vest     8 years 4 months 28 days          
Total intrinsic value of options exercised     $ 8,104,833          
Exercise of stock options (in shares)     755,463         755,463
Options exercised average exercise price (in usd per share)     $ 2.382         $ 2.382
Proceeds from exercises of options 735,839 2,585,997 1,799,271 4,002,088        
Options expiration period         10 years      
Options vesting period         5 years 5 years    
Options cliff vesting percentage           20.00%    
Options cliff vesting period           1 year    
Options ratable vesting percentage         20.00% 5.00%    
Options ratable vesting frequency         1 year 3 months    
Options ratable vesting period         5 years      
Options postemployment exercisable period         90 days      
Stock-based compensation expense 892,607 735,526 1,674,060 1,594,576        
Non-vested stock options unrecognized compensation expense         $ 7,888,875      
Non-vested stock options unrecognized compensation expense, weighted-average period of recognition         3 years 5 months 5 days