Equity Compensation (Details 4) (Stock options, USD $)
3 Months Ended 6 Months Ended
Jun. 30, 2014
Jun. 30, 2013
Jun. 30, 2014
Jun. 30, 2013
Total stock-based compensation expense        
Total stock-based compensation expense $ 1,408,000 $ 870,000 $ 2,655,000 $ 1,708,000
Total unrecognized compensation cost related to non-vested stock option awards 16,000,000   16,000,000  
Weighted-average period over which unrecognized compensation cost will be recognized     3 years 1 month 6 days  
Cost of revenue
       
Total stock-based compensation expense        
Total stock-based compensation expense 28,000 15,000 48,000 31,000
Research and development
       
Total stock-based compensation expense        
Total stock-based compensation expense 642,000 319,000 1,120,000 555,000
Sales and marketing
       
Total stock-based compensation expense        
Total stock-based compensation expense 292,000 172,000 514,000 356,000
General and administrative
       
Total stock-based compensation expense        
Total stock-based compensation expense $ 446,000 $ 364,000 $ 973,000 $ 766,000