Fair Value of Financial Assets and Liabilities (Tables)
 12 Months Ended
Dec. 31, 2015
Fair Value Disclosures [Abstract]  
Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis

The following tables present information about the Company’s assets and liabilities that are measured at fair value on a recurring basis as of December 31, 2015 and 2014 and indicate the level of the fair value hierarchy utilized to determine such fair value:

 

     Fair Value Measurements as of
December 31, 2015 Using:		  
     Level 1      Level 2      Level 3      Total  

Assets:

            

Cash equivalents:

            

Money market funds

    $ —        $ 29,879       $ —        $ 29,879   

Marketable securities:

            

United States treasury notes

      —           44,534         —           44,534   

Agency bonds

      —           29,746         —           29,746   
  

 

 

     

 

 

     

 

 

     

 

 

  

Total

    $ —         $ 104,159       $ —         $ 104,159   
  

 

 

     

 

 

     

 

 

     

 

 

  
     Fair Value Measurements as of
December 31, 2014 Using:		  
     Level 1      Level 2      Level 3      Total  

Assets:

            

Cash equivalents:

            

Money market funds

    $ —         $ 29,103       $ —         $ 29,103   

Agency bonds

      —           7,599         —           7,599   

Marketable securities:

            

United States treasury notes

      —           10,026         —           10,026   

Agency bonds

      —           27,409         —           27,409   
  

 

 

     

 

 

     

 

 

     

 

 

  

Total

    $ —         $ 74,137       $ —         $ 74,137   
  

 

 

     

 

 

     

 

 

     

 

 

  

Schedule of Aggregate Fair Values of Preferred Stock Warrants Determined by Level 3 Inputs

The following table provides a rollforward of the aggregate fair values of the Company’s preferred stock warrants for which fair value was determined by level 3 inputs:

 

Balance, January 1, 2013

    $ 268   

Decrease in fair value

      (14 ) 
  

 

 

  

Balance, December 31, 2013

      254   

Issuance of Series D-1 warrants

      326   

Increase in fair value

      380   

Conversion of preferred stock warrants to common stock warrants (Note 8)

      (960 ) 
  

 

 

  

Balance, December 31, 2014

    $ —