Quarterly report pursuant to Section 13 or 15(d)

Share-Based Compensation - Additional Information (Details)

v3.19.3
Share-Based Compensation - Additional Information (Details) - USD ($)
$ / shares in Units, $ in Thousands
6 Months Ended 9 Months Ended
Dec. 05, 2018
Oct. 14, 2016
Oct. 14, 2015
Jun. 30, 2019
Sep. 30, 2019
Sep. 30, 2018
Dec. 31, 2018
Mar. 14, 2018
May 18, 2017
Nov. 18, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                    
Ordinary shares, shares issued         14,868,973   14,352,046      
Share options awarded         512,178          
Restricted Ordinary Shares                    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                    
Shares issued in the period     413,110              
Percentage of remaining restricted ordinary shares vest on monthly basis   0.0278%                
Grant date fair value         $ 3.14   $ 3.14     $ 3.14
Expense recognized         $ 247 $ 249        
Unamortized stock compensation expense         $ 13 $ 344        
Stock-based compensation expense, expected weighted average period for recognition         14 days 1 year 14 days        
Number of shares, outstanding         8,542   86,068      
Restricted Ordinary Shares | Tranche One                    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                    
Percentage of awards vested   25.00%                
Employee Stock Options                    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                    
Expense recognized         $ 1,019 $ 459        
Unvested employee options outstanding         880,529 663,916        
Unamortized compensation expense share options         $ 3,711 $ 3,320        
Vesting period         2 years 10 months 2 days 3 years 6 months 10 days        
Restricted Share Units (RSUs)                    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                    
Grant date fair value         $ 7.01   $ 13.00      
Expense recognized         $ 257 $ 170        
Unamortized stock compensation expense         $ 154 $ 311        
Stock-based compensation expense, expected weighted average period for recognition         8 months 12 days 7 months 24 days        
Number of shares, granted/awarded         31,367 36,924        
Number of shares, outstanding         31,367   36,924      
Restricted Share Units (RSUs) | Director                    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                    
Vesting period         1 year          
Performance RSUs                    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                    
Grant date fair value       $ 8.21            
Expense recognized         $ 151          
Unamortized stock compensation expense         $ 259          
Stock-based compensation expense, expected weighted average period for recognition         1 year 21 days          
Number of shares, granted/awarded       50,000 50,000 0        
Number of shares, outstanding       50,000   0        
Restricted Ordinary Shares, Options and Restricted Share Units and Performance Restricted Share Units                    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                    
Vesting period         2 years 7 months 28 days 3 years 1 month 2 days        
Unamortized compensation expense         $ 4,137 $ 3,975        
2018 Plan                    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                    
Number of shares authorized               1,018,459   223,424
Number of ordinary shares available for issuance                 443,029 219,605
Increase in number of ordinary shares available to be granted, percentage 4.00%                  
Ordinary shares, shares issued             574,081      
2018 Plan | Employee Stock Options                    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]                    
Share options awarded         512,178 447,984