Annual report pursuant to Section 13 and 15(d)

Redeemable Convertible Preferred Stock - Additional Information (Detail)

v3.8.0.1
Redeemable Convertible Preferred Stock - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
 1 Months Ended 12 Months Ended
May 17, 2017
Jul. 31, 2016
Jul. 31, 2014
Dec. 31, 2017
Dec. 31, 2016
May 31, 2017
Apr. 30, 2017
Class of Stock [Line Items]              
Stock issued during period, Shares       13,538,080      
Preferred stock conversion basis         In the conversion to common stock, the holders of the redeemable convertible preferred stock would receive one share of the Company's common stock for each share of redeemable convertible preferred stock multiplied by the share's liquidation preference divided by its original issue price.    
Minimum proceeds from initial public offering that converts preferred stock into common stock         $ 15,000    
Net book value         $ 23,350    
Preferred Stock, authorized           1,000,000 11,500,000
Preferred Stock, par value             $ 0.001
Series A-1 Redeemable Convertible Preferred Stock [Member]              
Class of Stock [Line Items]              
Stock issued during period, Shares     2,666,667        
Series A Redeemable Convertible Preferred Stock [Member]              
Class of Stock [Line Items]              
Stock issued during period, Shares     3,000,000        
Share price       $ 1.76      
Net NM's asset book value       $ 1,500      
Preferred stock redemption terms         The preferred stock was redeemable at any time after July 15, 2019 if the holders of the minimum number of outstanding shares made that election.    
Preferred stock, liquidation preference per share         $ 2.14    
Liquidation preference value $ 8,598            
Net book value $ 6,272       $ 5,453    
Shares converted to common stock 2,922,798     2,922,798      
Change in liquidation preference and net book value $ 2,326            
Debt beneficial conversion feature       $ 328      
Debt amortization of discount       96      
Write-off of unamortized portion of beneficial conversion feature       $ 232      
Preferred Stock, authorized       0 5,666,667    
Preferred Stock, par value       $ 0.001 $ 0.001    
Series B Redeemable Convertible Preferred Stock [Member]              
Class of Stock [Line Items]              
Stock issued during period, Shares     3,092,781        
Share price     $ 4.85        
Proceeds from Preferred stock issue     $ 15,000        
Preferred stock, liquidation preference per share         $ 5.86    
Liquidation preference value 18,668            
Net book value $ 18,463       $ 17,897    
Shares converted to common stock 2,309,135     2,309,135      
Change in liquidation preference and net book value $ 205            
Debt beneficial conversion feature       $ 226      
Debt amortization of discount       67      
Write-off of unamortized portion of beneficial conversion feature       $ 159      
Preferred Stock, authorized       0 3,092,781    
Preferred Stock, par value       $ 0.001 $ 0.001    
Redeemable Convertible Preferred Stock [Member]              
Class of Stock [Line Items]              
Preferred stock conversion basis   All outstanding shares of Series A-1 preferred stock were converted on a one-for-one basis into shares of Series A preferred stock.