v3.26.1
Share-based compensation - Share-based compensation-Share options-2011 Share Incentive Scheme (Details) - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Forfeited ,Options     (840,180)  
Forfeited ,weighted average exercise price     $ 3.535  
Balance ,contractual life       1 year 9 months 18 days
2011 Incentive Scheme        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Balance ,options 8,074,500 8,574,220 9,414,400  
Forfeited ,Options   (499,720)    
Balance ,options 8,074,500 8,074,500 8,574,220 9,414,400
Expected to vest at December 31 ,options 8,074,500      
Exercisable at December 31, options 8,074,500      
Balance, weighted average exercise price $ 3.8436 $ 3.8256 $ 3.7997  
Forfeited ,weighted average exercise price   3.535    
Balance, weighted average exercise price 3.8436 $ 3.8436 $ 3.8256 $ 3.7997
Expected to vest at December 31, weighted average exercise price 3.8436      
Exercisable at December 31, weighted average exercise price $ 3.8436      
Balance ,contractual life 4 months 17 days 9 months 3 days 1 year 7 months 9 days  
Expected to vest at December 31, contractual life 4 months 17 days      
Exercisable at December 31, contractual life 4 months 17 days      
Expected to vest at December 31, aggregate intrinsic value $ 0      
Total intrinsic value $ 0 $ 0 $ 0