v3.26.1
Risk management - Disclosure of concentrations, credit with mortgage guarantee to households for house acquisition (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
Gross carrying amount | Property assets from home purchase mortgage loans to households | Spain      
Disclosure of credit risk exposure [line items]      
Financial assets 60,002 59,316 61,097
Gross carrying amount | Property assets from home purchase mortgage loans to households | Spain | Credit impaired      
Disclosure of credit risk exposure [line items]      
Financial assets 625 789 924
With mortgage collateral | Gross carrying amount | Property assets from home purchase mortgage loans to households | Spain      
Disclosure of credit risk exposure [line items]      
Financial assets 59,787 59,108 60,882
With mortgage collateral | Gross carrying amount | Property assets from home purchase mortgage loans to households | Spain | Credit impaired      
Disclosure of credit risk exposure [line items]      
Financial assets 618 € 778 € 908
Less than or equal to 40% | With mortgage collateral | Gross carrying amount | Property assets from home purchase mortgage loans to households | Spain      
Disclosure of credit risk exposure [line items]      
Financial assets 17,191    
Less than or equal to 40% | With mortgage collateral | Gross carrying amount | Property assets from home purchase mortgage loans to households | Spain | Credit impaired      
Disclosure of credit risk exposure [line items]      
Financial assets 122    
More than 40% and less than or equal to 60% | With mortgage collateral | Gross carrying amount | Property assets from home purchase mortgage loans to households | Spain      
Disclosure of credit risk exposure [line items]      
Financial assets 20,310    
More than 40% and less than or equal to 60% | With mortgage collateral | Gross carrying amount | Property assets from home purchase mortgage loans to households | Spain | Credit impaired      
Disclosure of credit risk exposure [line items]      
Financial assets 158    
More than 60% and less than or equal to 80% | With mortgage collateral | Gross carrying amount | Property assets from home purchase mortgage loans to households | Spain      
Disclosure of credit risk exposure [line items]      
Financial assets 18,811    
More than 60% and less than or equal to 80% | With mortgage collateral | Gross carrying amount | Property assets from home purchase mortgage loans to households | Spain | Credit impaired      
Disclosure of credit risk exposure [line items]      
Financial assets 151    
More than 80% and less than or equal to 100% | With mortgage collateral | Gross carrying amount | Property assets from home purchase mortgage loans to households | Spain      
Disclosure of credit risk exposure [line items]      
Financial assets 2,812    
More than 80% and less than or equal to 100% | With mortgage collateral | Gross carrying amount | Property assets from home purchase mortgage loans to households | Spain | Credit impaired      
Disclosure of credit risk exposure [line items]      
Financial assets 84    
More than 100% | With mortgage collateral | Gross carrying amount | Property assets from home purchase mortgage loans to households | Spain      
Disclosure of credit risk exposure [line items]      
Financial assets 663    
More than 100% | With mortgage collateral | Gross carrying amount | Property assets from home purchase mortgage loans to households | Spain | Credit impaired      
Disclosure of credit risk exposure [line items]      
Financial assets € 103