Annual report pursuant to Section 13 and 15(d)

Redeemable Convertible Preferred Stock - Additional Information (Detail)

v3.19.1
Redeemable Convertible Preferred Stock - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
 1 Months Ended 12 Months Ended
Jun. 25, 2018
Nov. 21, 2017
May 17, 2017
Mar. 31, 2017
Jul. 31, 2014
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
May 31, 2017
Apr. 30, 2017
Class of Stock [Line Items]                    
Stock issued during period, Shares 1,955,000 1,121,250   120,000            
Share price $ 18.00 $ 23                
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    
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              
Shares converted to common stock     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      
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              
Shares converted to common stock     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      
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.