v3.25.4
Risk management - Revaluation reserve equity securities at fair value through other comprehensive income (Details) - EUR (€)
€ in Millions
12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Disclosure of fair value measurement of equity [line items]    
Investments in other group companies € 1,607 € 1,679
Revaluation reserve equity securities    
Disclosure of fair value measurement of equity [line items]    
Increase (decrease) in financial assets (372)  
Financial assets (1,444) (1,816)
Revaluation reserve equity securities | Bank Of Beijing    
Disclosure of fair value measurement of equity [line items]    
Increase (decrease) in financial assets (403)  
Equity securities at FVOCI    
Disclosure of fair value measurement of equity [line items]    
Investments in other group companies 2,607 2,562
Increase (decrease) in financial assets (45)  
Revaluation reserves: financial assets 1,444 1,816
Positive remeasurement | Equity securities at FVOCI    
Disclosure of fair value measurement of equity [line items]    
Revaluation reserves: financial assets 1,456 1,820
Negative remeasurement | Equity securities at FVOCI    
Disclosure of fair value measurement of equity [line items]    
Revaluation reserves: financial assets € (12) € (4)