Related Party Transactions
 12 Months Ended
Dec. 31, 2013
Related Party Transactions  
Related Party Transactions

9. Related Party Transactions

        The Company has entered into sales agreements with certain of its investors. The following table sets forth revenue from product sales to companies affiliated with these investors (in thousands):

 
   Years Ended December 31,  
 
   2011   2012   2013  

Company 1

   $ 995   $ 2,142   $ 2,889  

Company 2

     2,134     1,290     950  

Company 3

     478     791     426  

Company 4

     —     1,807     129  
               
​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

 

   $ 3,607   $ 6,030   $ 4,394  
               
​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
               

        As of December 31, 2012 and 2013, the Company had accounts receivable from these companies totaling $1.5 million and $0.6 million, respectively. Purchase and payment terms with these related parties are consistent with other non-affiliated companies.