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Nature of Business - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
 1 Months Ended 12 Months Ended
Sep. 29, 2016
Dec. 03, 2014
May 13, 2011
Jan. 31, 2015
Dec. 31, 2016
Dec. 31, 2015
Nature Of Business And Basis Of Presentation [Line Items]            
Proceeds from issuance of issuance of common stock, preferred stock and warrants, net of issuance costs $ 27,600       $ 27,630  
Accumulated deficit         $ (181,773) $ (165,565)
Net proceeds from initial public offering   $ 61,300        
ProChon [Member]            
Nature Of Business And Basis Of Presentation [Line Items]            
Business acquisition date         May 13, 2011  
Consideration paid to acquisition     $ 2,200      
IPO [Member]            
Nature Of Business And Basis Of Presentation [Line Items]            
Sale of common stock shares   5,909,091        
Initial public offering price per share   $ 11.00        
Gross proceeds from initial public offering   $ 65,000        
Overallotment Option [Member]            
Nature Of Business And Basis Of Presentation [Line Items]            
Sale of common stock shares       465,000    
Initial public offering price per share       $ 11.00    
Gross proceeds from initial public offering       $ 5,100