v3.25.4
Derivatives and hedge accounting - Hedged items included in a fair value hedging relationship (Details) - -  fair value hedges - EUR (€)
€ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Disclosure of detailed information about hedged items [line items]      
Change in fair value hedging instruments for the period € 1,111 € 1,016 € 1,606
Interest Rate And Forex Risk | - Derivatives      
Disclosure of detailed information about hedged items [line items]      
Hedged item, assets 65,690 50,070  
Hedged item, liabilities 102,663 100,827  
Accumulated fair value hedge adjustment remaining in statement of financial position for hedged item that ceased to be adjusted for hedging gains and losses, assets 33 58  
Carrying amount net investment hedge reserve at the end of the reporting period (407) (126)  
Accumulated fair value hedge adjustment remaining in statement of financial position for hedged item that ceased to be adjusted for hedging gains and losses, liabilities (1) (5)  
Accumulated fair value hedge adjustment on hedged item included in carrying amount, liabilities (2,456) (2,906)  
Change in fair value of the hedged item for measuring ineffectiveness for the period (1,078) (1,043)  
Change in fair value hedging instruments for the period 1,111 1,016  
Hedge ineffectiveness recognised in the statement of profit or loss gain (+) / loss (-) 34 (27)  
- Debt securities | Interest Rate And Forex Risk | - Derivatives      
Disclosure of detailed information about hedged items [line items]      
Hedged item, liabilities 85,843 83,669  
Accumulated fair value hedge adjustment remaining in statement of financial position for hedged item that ceased to be adjusted for hedging gains and losses, liabilities (2,127) (2,234)  
Change in fair value of the hedged item for measuring ineffectiveness for the period (45) (1,139)  
- Debt securities | Financial assets at FVOCI | Interest Rate And Forex Risk | - Derivatives      
Disclosure of detailed information about hedged items [line items]      
Hedged item, assets 44,165 35,119  
Change in fair value of the hedged item for measuring ineffectiveness for the period (480) 269  
- Debt securities | Financial assets at amortised cost | Interest Rate And Forex Risk | - Derivatives      
Disclosure of detailed information about hedged items [line items]      
Hedged item, assets 20,695 13,802  
Accumulated fair value hedge adjustment remaining in statement of financial position for hedged item that ceased to be adjusted for hedging gains and losses, assets (438) (179)  
Change in fair value of the hedged item for measuring ineffectiveness for the period (284) 49  
– Loans at FVOCI | Financial assets at FVOCI | Interest Rate And Forex Risk | - Derivatives      
Disclosure of detailed information about hedged items [line items]      
Change in fair value of the hedged item for measuring ineffectiveness for the period    
– Loans and advances to customers | Interest Rate And Forex Risk | - Derivatives      
Disclosure of detailed information about hedged items [line items]      
Hedged item, assets 830 1,149  
Accumulated fair value hedge adjustment remaining in statement of financial position for hedged item that ceased to be adjusted for hedging gains and losses, assets (2) (6)  
Change in fair value of the hedged item for measuring ineffectiveness for the period 19 (35)  
– Subordinated loans | Interest Rate And Forex Risk | - Derivatives      
Disclosure of detailed information about hedged items [line items]      
Hedged item, liabilities 16,794 17,131  
Accumulated fair value hedge adjustment remaining in statement of financial position for hedged item that ceased to be adjusted for hedging gains and losses, liabilities (327) (665)  
Change in fair value of the hedged item for measuring ineffectiveness for the period (287) (188)  
– Customer deposits and other funds on deposit | Interest Rate And Forex Risk | - Derivatives      
Disclosure of detailed information about hedged items [line items]      
Hedged item, liabilities 26 28  
Accumulated fair value hedge adjustment remaining in statement of financial position for hedged item that ceased to be adjusted for hedging gains and losses, liabilities (1) (1)  
Change in fair value of the hedged item for measuring ineffectiveness for the period € 1