Redeemable Convertible Preferred Stock (Tables)
12 Months Ended
Dec. 31, 2015
Series C Redeemable Convertible Preferred Stock [Member]  
Summary of Estimated Fair Values of Outstanding Warrants Using Black-Scholes Option-Pricing Model

The fair value of the Series C preferred stock warrants as of the IPO closing date was $2.3 million and was determined using the Black-Scholes option-pricing model with the following assumptions:

 

     FEBRUARY 4,
2014
 

Stock price

   $ 32.66   

Expected option term (in years)

     4.39   

Expected volatility

     65

Risk-free interest rate

     1.52

Expected dividend yield

     0.00