v3.26.1
Risk management - Disclosure of concentrations, Spain real estate business (Details) - EUR (€)
€ in Millions
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Disclosure of credit risk exposure [line items]      
Financial assets € 300,026 € 283,497 € 243,203
Spain | Real estate operations in Spain | Gross carrying amount      
Disclosure of credit risk exposure [line items]      
Financial assets 2,984    
Spain | Real estate operations in Spain | Gross carrying amount | Without mortgage collateral      
Disclosure of credit risk exposure [line items]      
Financial assets 14    
Spain | Real estate operations in Spain | Gross carrying amount | With mortgage collateral      
Disclosure of credit risk exposure [line items]      
Financial assets 2,970    
Spain | Real estate operations in Spain | Gross carrying amount | Buildings for own use | With mortgage collateral      
Disclosure of credit risk exposure [line items]      
Financial assets 976    
Spain | Real estate operations in Spain | Gross carrying amount | Buildings for own use | Residential      
Disclosure of credit risk exposure [line items]      
Financial assets 658    
Spain | Real estate operations in Spain | Gross carrying amount | Buildings for own use | Other      
Disclosure of credit risk exposure [line items]      
Financial assets 318    
Spain | Real estate operations in Spain | Gross carrying amount | Construction in progress | With mortgage collateral      
Disclosure of credit risk exposure [line items]      
Financial assets 1,981    
Spain | Real estate operations in Spain | Gross carrying amount | Construction in progress | Residential      
Disclosure of credit risk exposure [line items]      
Financial assets 1,913    
Spain | Real estate operations in Spain | Gross carrying amount | Construction in progress | Other      
Disclosure of credit risk exposure [line items]      
Financial assets 68    
Spain | Real estate operations in Spain | Gross carrying amount | Land | With mortgage collateral      
Disclosure of credit risk exposure [line items]      
Financial assets 13    
Spain | Real estate operations in Spain | Gross carrying amount | Land | Developed consolidated land      
Disclosure of credit risk exposure [line items]      
Financial assets 9    
Spain | Real estate operations in Spain | Gross carrying amount | Land | Other land      
Disclosure of credit risk exposure [line items]      
Financial assets € 4