v3.26.1
Financial risk management - Disclosure of internal credit exposures explanatory (Detail)
Dec. 31, 2025
Dec. 31, 2024
High grade [member] | Small Business Banking    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 5.20% 8.55%
Standard grade [member] | Small Business Banking | Bottom of range [member]    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 5.21% 8.56%
Standard grade [member] | Small Business Banking | Top of range [member]    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 14.24% 17.86%
Sub-standard grade [member] | Small Business Banking    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 14.25% 17.87%
Credit card | High grade [member] | Personal Banking    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 4.55% 5.25%
Credit card | Standard grade [member] | Personal Banking | Bottom of range [member]    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 4.56% 5.26%
Credit card | Standard grade [member] | Personal Banking | Top of range [member]    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 10.32% 12.05%
Credit card | Sub-standard grade [member] | Personal Banking    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 10.33% 12.06%
Mortgage loans [member] | High grade [member] | Personal Banking    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 1.51% 1.12%
Mortgage loans [member] | Standard grade [member] | Personal Banking | Bottom of range [member]    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 1.52% 1.13%
Mortgage loans [member] | Standard grade [member] | Personal Banking | Top of range [member]    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 4.93% 3.55%
Mortgage loans [member] | Sub-standard grade [member] | Personal Banking    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 4.94% 3.56%
Payroll Loans | High grade [member] | Personal Banking    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 2.63% 2.36%
Payroll Loans | Standard grade [member] | Personal Banking | Bottom of range [member]    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 2.64% 2.37%
Payroll Loans | Standard grade [member] | Personal Banking | Top of range [member]    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 6.13% 5.15%
Payroll Loans | Sub-standard grade [member] | Personal Banking    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 6.14% 5.16%
Consumer | High grade [member] | Personal Banking    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 6.81% 7.11%
Consumer | Standard grade [member] | Personal Banking    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 6.82%  
Consumer | Standard grade [member] | Personal Banking | Bottom of range [member]    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage   7.12%
Consumer | Standard grade [member] | Personal Banking | Top of range [member]    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 14.93% 14.68%
Consumer | Sub-standard grade [member] | Personal Banking    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 14.94% 14.69%
Vehicular | High grade [member] | Personal Banking    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 5.88% 3.76%
Vehicular | Standard grade [member] | Personal Banking    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 5.88% 3.76%
Vehicular | Sub-standard grade [member] | Personal Banking    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 5.88% 3.76%
Corporate | High grade [member] | Small Business Banking    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 0.22% 0.10%
Corporate | Standard grade [member] | Small Business Banking | Bottom of range [member]    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 0.23% 0.11%
Corporate | Standard grade [member] | Small Business Banking | Top of range [member]    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 0.44% 0.20%
Corporate | Sub-standard grade [member] | Small Business Banking    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 0.45% 0.21%
Institutional | High grade [member] | Commercial Banking    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 0.31% 0.66%
Institutional | Standard grade [member] | Commercial Banking    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 0.31% 0.66%
Institutional | Sub-standard grade [member] | Commercial Banking    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 0.31% 0.66%
Companies | High grade [member] | Commercial Banking    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 0.79% 3.45%
Companies | Standard grade [member] | Commercial Banking | Bottom of range [member]    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 0.80% 3.46%
Companies | Standard grade [member] | Commercial Banking | Top of range [member]    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 2.31% 8.13%
Companies | Sub-standard grade [member] | Commercial Banking    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 2.32% 8.14%
Real Estate | High grade [member] | Commercial Banking    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 0.31% 2.61%
Real Estate | Standard grade [member] | Commercial Banking    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 0.31% 2.61%
Real Estate | Sub-standard grade [member] | Commercial Banking    
Disclosure of internal credit grades [line items]    
Probability Of Default Range Percentage 0.31% 2.61%