v3.25.4
Material Accounting Policies and Critical Accounting Estimates (Detail: Text Values)
€ in Billions
 12 Months Ended
Dec. 31, 2025
EUR (€)
Dec. 31, 2024
EUR (€)
Impact of the EU carve-out version of IAS 39    
Positive (negative) impact on profit before tax, EU Carve Out € 0.7 € (1.4)
Positive (negative) impact on profit after tax, EU Carve Out € 0.3 € (1.0)
Impact on CET 1 capital ratio, EU Carve Out, (less than) in bps 0.0060 0.0068
Principles of Consolidation - Associates    
Group recognize a loss allowance at an amount equal to lifetime expected credit losses, percent 0.20  
Significant influence is generally presumed when the Group holds voting rights in an upper range, percent 50.00%  
Groups investment of the voting stock, percent 20.00%  
Customer-
related
intangible
assets | Bottom of range    
Disclosure of detailed information about intangible assets [line items]    
Useful lives
in years 1 year  
Customer-
related
intangible
assets | Top of range    
Disclosure of detailed information about intangible assets [line items]    
Useful lives
in years 15 years  
Computer software, useful life 1    
Disclosure of detailed information about intangible assets [line items]    
Useful lives
in years 3 years  
Computer software, useful life 2    
Disclosure of detailed information about intangible assets [line items]    
Useful lives
in years 5 years  
Computer software, useful life 3    
Disclosure of detailed information about intangible assets [line items]    
Useful lives
in years 10 years  
Owner occupied properties | Bottom of range    
Disclosure of detailed information about property, plant and equipment [line items]    
Useful of property and equipment 25 years  
Owner occupied properties | Top of range    
Disclosure of detailed information about property, plant and equipment [line items]    
Useful of property and equipment 50 years  
Furniture and equipment | Bottom of range    
Disclosure of detailed information about property, plant and equipment [line items]    
Useful of property and equipment 3 years  
Furniture and equipment | Top of range    
Disclosure of detailed information about property, plant and equipment [line items]    
Useful of property and equipment 10 years  
Leasehold improvements | Bottom of range    
Disclosure of detailed information about property, plant and equipment [line items]    
Useful of property and equipment 3 years  
Leasehold improvements | Top of range    
Disclosure of detailed information about property, plant and equipment [line items]    
Useful of property and equipment 25 years