v3.26.1
Expected credit loss measurement - ECL-relevant balance sheet and off-balance sheet positions including ECL allowances and provisions (Narrative) (Detail)
 6 Months Ended
Jun. 30, 2026
Dec. 31, 2025
Disclosure Of Provision Matrix [Line Items]    
ECL coverage 0.35% 0.31%
Stage 1 and 2 positions    
Disclosure Of Provision Matrix [Line Items]    
ECL coverage 0.11% 0.10%
Increase decrease in ECL coverage 0.01%  
Allowance for expected credit loss | On-balance sheet    
Disclosure Of Provision Matrix [Line Items]    
ECL coverage 0.38% 0.38%
Allowance for expected credit loss | Real estate lending (on-balance sheet) | On-balance sheet    
Disclosure Of Provision Matrix [Line Items]    
ECL coverage 0.05% 0.05%
Allowance for expected credit loss | Corporate lending (on-balance sheet) | On-balance sheet    
Disclosure Of Provision Matrix [Line Items]    
ECL coverage 3.43% 3.49%
Allowance for expected credit loss | Stage 1 and 2 positions | On-balance sheet    
Disclosure Of Provision Matrix [Line Items]    
ECL coverage 0.10% 0.10%
Allowance for expected credit loss | Stage 1 and 2 positions | Real estate lending (on-balance sheet) | On-balance sheet    
Disclosure Of Provision Matrix [Line Items]    
ECL coverage 0.03% 0.03%
Allowance for expected credit loss | Stage 1 and 2 positions | Corporate lending (on-balance sheet) | On-balance sheet    
Disclosure Of Provision Matrix [Line Items]    
ECL coverage 0.79% 0.76%
Increase decrease in ECL coverage 0.03%