v3.25.2
Intangible assets - Schedule of goodwill based on cash-generating units (Details) - EUR (€)
€ in Millions
Jun. 30, 2025
Dec. 31, 2024
Disclosure of information for cash-generating units [line items]    
Goodwill € 11,960 € 13,438
Banco Santander (Brazil)    
Disclosure of information for cash-generating units [line items]    
Goodwill 3,061 3,079
SAM Investment Holdings Limited    
Disclosure of information for cash-generating units [line items]    
Goodwill 1,444 1,444
Santander Consumer Germany    
Disclosure of information for cash-generating units [line items]    
Goodwill 1,304 1,304
Santander Portugal    
Disclosure of information for cash-generating units [line items]    
Goodwill 1,040 1,040
Santander España    
Disclosure of information for cash-generating units [line items]    
Goodwill 998 998
Santander US Auto    
Disclosure of information for cash-generating units [line items]    
Goodwill 944 1,068
Santander Holding USA (ex. Auto)    
Disclosure of information for cash-generating units [line items]    
Goodwill 765 865
Santander UK    
Disclosure of information for cash-generating units [line items]    
Goodwill 620 641
Banco Santander - Chile    
Disclosure of information for cash-generating units [line items]    
Goodwill 454 482
Grupo Financiero Santander (Mexico)    
Disclosure of information for cash-generating units [line items]    
Goodwill 441 453
Ebury Partners    
Disclosure of information for cash-generating units [line items]    
Goodwill 329 340
Santander Consumer Nordics    
Disclosure of information for cash-generating units [line items]    
Goodwill 211 211
Santander Bank Polska    
Disclosure of information for cash-generating units [line items]    
Goodwill 0 1,178
Other entities    
Disclosure of information for cash-generating units [line items]    
Goodwill € 349 € 335