v3.25.4
Premises, equipment and computer software - Schedule of Premise, Equipment and Computer Software (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Property, Plant and Equipment [Line Items]      
Cost $ 332,290 $ 342,499  
Accumulated depreciation (173,786) (188,717)  
Net carrying value 158,504 153,782  
Total depreciation charged to operating expenses 21,343 21,354 $ 19,767
Land      
Property, Plant and Equipment [Line Items]      
Cost 8,333 8,333  
Accumulated depreciation 0 0  
Net carrying value 8,333 8,333  
Buildings      
Property, Plant and Equipment [Line Items]      
Cost 215,735 204,473  
Accumulated depreciation (97,538) (91,401)  
Net carrying value 118,197 113,072  
Total depreciation charged to operating expenses 10,156 9,202 7,334
Equipment      
Property, Plant and Equipment [Line Items]      
Cost 28,222 27,128  
Accumulated depreciation (20,250) (19,304)  
Net carrying value 7,972 7,824  
Total depreciation charged to operating expenses 2,406 2,384 2,389
Computer hardware and software in use      
Property, Plant and Equipment [Line Items]      
Cost 75,394 100,630  
Accumulated depreciation (55,998) (78,012)  
Net carrying value 19,396 22,618  
Total depreciation charged to operating expenses 8,781 9,768 $ 10,044
Computer software in development      
Property, Plant and Equipment [Line Items]      
Cost 4,606 1,935  
Accumulated depreciation 0 0  
Net carrying value $ 4,606 $ 1,935