Nature of Business - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
 12 Months Ended
Dec. 08, 2015
Dec. 03, 2014
May. 13, 2011
Dec. 31, 2015
Dec. 31, 2014
Mar. 31, 2015
Dec. 08, 2014
Jul. 09, 2014
Jul. 20, 2012
Nature Of Business And Basis Of Presentation [Line Items]                  
Gross proceeds from initial public offering         $ 60,450        
Net proceeds from initial public offering   $ 56,539              
Conversion of redeemable preferred stock and accrued dividends 5,158,407 5,158,407     4,558,483        
Net exercise of warrants, shares   44,531   156,138 156,138 7,398 44,531 6,566 161,977
Surrender of warrant to satisfy other liability   5,839              
Additional paid-in capital       $ 193,631 $ 187,620        
Common stock, shares authorized   100,000,000   100,000,000 100,000,000        
Preferred stock shares authorized   10,000,000              
ProChon [Member]                  
Nature Of Business And Basis Of Presentation [Line Items]                  
Business acquisition date       May 13, 2011          
Consideration paid to acquisition     $ 2,224            
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              
Convertible notes payable to common stock   $ 11,100     $ 11,100        
Accrued interest to common stock   1,009,115              
Warrant Liability [Member]                  
Nature Of Business And Basis Of Presentation [Line Items]                  
Additional paid-in capital   $ 490              
Other Liability [Member]                  
Nature Of Business And Basis Of Presentation [Line Items]                  
Additional paid-in capital   $ 612