Nature of Business and Operations - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
 12 Months Ended
Apr. 10, 2015
May. 07, 2014
Apr. 15, 2014
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Nature Of Business And Operations [Line Items]            
Date of Company's incorporation       Nov. 28, 2005    
Accumulated deficit       $ 161,375 $ 121,781  
Proceeds from sale of common stock       $ 2,628 $ 140 $ 35
Common Stock [Member]            
Nature Of Business And Operations [Line Items]            
Issuance and sale of common stock, Shares 6,716,000          
Follow-on Offering [Member]            
Nature Of Business And Operations [Line Items]            
Common stock issuance date       Apr. 10, 2015    
Issuance and sale of common stock, Shares 6,716,000          
Common share offering price, per share $ 6.00          
Proceeds from sale of common stock $ 37,200          
Follow-on Offering [Member] | Common Stock [Member]            
Nature Of Business And Operations [Line Items]            
Issuance and sale of common stock, Shares       6,716,000    
Option Exercised by Underwriter [Member]            
Nature Of Business And Operations [Line Items]            
Issuance and sale of common stock, Shares 876,000          
IPO [Member]            
Nature Of Business And Operations [Line Items]            
Common stock issuance date         Apr. 15, 2014  
Issuance and sale of common stock, Shares   1,069,715 8,500,000      
Issuance/sale of stock, price per share   $ 7.00 $ 7.00      
Proceeds from initial public offering, net   $ 59,900        
Preferred stock conversion basis       In connection with the closing of the IPO, all of the Company's outstanding redeemable convertible preferred stock and convertible notes automatically converted into shares of common stock as of April 15, 2014    
IPO [Member] | Preferred Stock Warrants [Member]            
Nature Of Business And Operations [Line Items]            
Warrant to purchase stock, number of securities called by warrants or rights     1,857,226      
IPO [Member] | Common Stock Warrants [Member]            
Nature Of Business And Operations [Line Items]            
Number of automatically converted shares     128,663      
IPO [Member] | Common Stock [Member]            
Nature Of Business And Operations [Line Items]            
Issuance and sale of common stock, Shares         9,569,715  
Number of automatically converted shares     9,728,237