v3.26.1
Financial Risks - Summary of Changes in Fair Value have been Recognized for these Investments (Detail) - EUR (€)
€ in Millions
12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Disclosure of changes in the fair value of financial assets designated at fair value through profit or loss [line items]    
Change in fair value attributable to changes in credit risk during the year € 8 € 19
Cumulative change in fair value attributable to changes in credit risk held on December 31 45 59
Loans [member]    
Disclosure of changes in the fair value of financial assets designated at fair value through profit or loss [line items]    
Change in fair value attributable to changes in credit risk during the year 1 3
Cumulative change in fair value attributable to changes in credit risk held on December 31 0 0
Debt securities [member]    
Disclosure of changes in the fair value of financial assets designated at fair value through profit or loss [line items]    
Change in fair value attributable to changes in credit risk during the year 7 16
Cumulative change in fair value attributable to changes in credit risk held on December 31 € 45 € 59