v3.26.1
Risk management - Disclosure of sensitivity analysis, by entity (Details)
Dec. 31, 2025
Spain  
Disclosure of credit risk exposure [line items]  
Change in provision assuming 100bp decrease in GDP growth rate (as a percent) 2.10%
Change in provision assuming 100bp increase in GDP growth rate (as a percent) (1.90%)
Change in provision assuming 100bp decrease in housing price change rate (as a percent) 3.40%
Change in provision assuming 100bp increase in housing price change rate (as a percent) (1.80%)
Change in provision assuming 100bp decrease in unemployment rate (as a percent) (3.70%)
Change in provision assuming 100bp increase in unemployment rate (as a percent) 4.70%
Mortgages | Spain  
Disclosure of credit risk exposure [line items]  
Change in provision assuming 100bp decrease in GDP growth rate (as a percent) 8.50%
Change in provision assuming 100bp increase in GDP growth rate (as a percent) (3.60%)
Change in provision assuming 100bp decrease in housing price change rate (as a percent) 8.40%
Change in provision assuming 100bp increase in housing price change rate (as a percent) (6.70%)
Change in provision assuming 100bp decrease in unemployment rate (as a percent) (6.00%)
Change in provision assuming 100bp increase in unemployment rate (as a percent) 14.70%
Mortgages | Santander UK plc  
Disclosure of credit risk exposure [line items]  
Change in provision assuming 100bp decrease in GDP growth rate (as a percent) 11.60%
Change in provision assuming 100bp increase in GDP growth rate (as a percent) (2.90%)
Change in provision assuming 100bp decrease in housing price change rate (as a percent) 7.30%
Change in provision assuming 100bp increase in housing price change rate (as a percent) (3.50%)
Change in provision assuming 100bp decrease in unemployment rate (as a percent) (12.30%)
Change in provision assuming 100bp increase in unemployment rate (as a percent) 23.70%
Mortgages | Santander Bank, National Association | US | Total North America  
Disclosure of credit risk exposure [line items]  
Change in provision assuming 100bp decrease in GDP growth rate (as a percent) 13.60%
Change in provision assuming 100bp increase in GDP growth rate (as a percent) (10.60%)
Change in provision assuming 100bp decrease in housing price change rate (as a percent) 26.90%
Change in provision assuming 100bp increase in housing price change rate (as a percent) (12.90%)
Change in provision assuming 100bp decrease in unemployment rate (as a percent) (41.60%)
Change in provision assuming 100bp increase in unemployment rate (as a percent) 53.90%
Change in provision assuming 100bp decrease in Manheim index (as a percent) 0.00%
Change in provision assuming 100bp increase in Manheim index (as a percent) 0.00%
Consumer loans | Banco Santander (Brasil) S.A. | Brazil | Total South America  
Disclosure of credit risk exposure [line items]  
Change in provision assuming 100bp decrease in GDP growth rate (as a percent) 1.30%
Change in provision assuming 100bp increase in GDP growth rate (as a percent) (0.70%)
Change in provision assuming 100bp decrease in unemployment rate (as a percent) (1.90%)
Change in provision assuming 100bp increase in unemployment rate (as a percent) 2.80%
Change in provision assuming 100bp decrease in interest rate (as a percent) (0.60%)
Change in provision assuming 100bp increase in interest rate (as a percent) 1.70%
SME | Banco Santander (Brasil) S.A. | Brazil | Total South America  
Disclosure of credit risk exposure [line items]  
Change in provision assuming 100bp decrease in GDP growth rate (as a percent) 2.90%
Change in provision assuming 100bp increase in GDP growth rate (as a percent) (1.30%)
Change in provision assuming 100bp decrease in unemployment rate (as a percent) (3.80%)
Change in provision assuming 100bp increase in unemployment rate (as a percent) 6.20%
Change in provision assuming 100bp decrease in interest rate (as a percent) (1.60%)
Change in provision assuming 100bp increase in interest rate (as a percent) 4.00%
Corporates | Spain  
Disclosure of credit risk exposure [line items]  
Change in provision assuming 100bp decrease in GDP growth rate (as a percent) 1.10%
Change in provision assuming 100bp increase in GDP growth rate (as a percent) (0.90%)
Change in provision assuming 100bp decrease in housing price change rate (as a percent) 1.50%
Change in provision assuming 100bp increase in housing price change rate (as a percent) (0.70%)
Change in provision assuming 100bp decrease in unemployment rate (as a percent) (1.50%)
Change in provision assuming 100bp increase in unemployment rate (as a percent) 1.80%
Corporates | Santander UK plc  
Disclosure of credit risk exposure [line items]  
Change in provision assuming 100bp decrease in GDP growth rate (as a percent) 3.90%
Change in provision assuming 100bp increase in GDP growth rate (as a percent) (1.40%)
Change in provision assuming 100bp decrease in housing price change rate (as a percent) 6.00%
Change in provision assuming 100bp increase in housing price change rate (as a percent) (1.60%)
Change in provision assuming 100bp decrease in unemployment rate (as a percent) (2.50%)
Change in provision assuming 100bp increase in unemployment rate (as a percent) 5.70%
Corporates | Santander Bank, National Association | US | Total North America  
Disclosure of credit risk exposure [line items]  
Change in provision assuming 100bp decrease in GDP growth rate (as a percent) 10.90%
Change in provision assuming 100bp increase in GDP growth rate (as a percent) (7.70%)
Change in provision assuming 100bp decrease in housing price change rate (as a percent) 18.70%
Change in provision assuming 100bp increase in housing price change rate (as a percent) (9.30%)
Change in provision assuming 100bp decrease in unemployment rate (as a percent) (25.90%)
Change in provision assuming 100bp increase in unemployment rate (as a percent) 39.50%
Change in provision assuming 100bp decrease in Manheim index (as a percent) 0.00%
Change in provision assuming 100bp increase in Manheim index (as a percent) 0.00%
Auto | Santander Bank, National Association | US | Total North America  
Disclosure of credit risk exposure [line items]  
Change in provision assuming 100bp decrease in GDP growth rate (as a percent) 2.80%
Change in provision assuming 100bp increase in GDP growth rate (as a percent) (2.00%)
Change in provision assuming 100bp decrease in housing price change rate (as a percent) 5.00%
Change in provision assuming 100bp increase in housing price change rate (as a percent) (2.50%)
Change in provision assuming 100bp decrease in unemployment rate (as a percent) (7.90%)
Change in provision assuming 100bp increase in unemployment rate (as a percent) 11.80%
Change in provision assuming 100bp decrease in Manheim index (as a percent) 1.80%
Change in provision assuming 100bp increase in Manheim index (as a percent) (1.40%)
Other | Banco Santander (Brasil) S.A. | Brazil | Total South America  
Disclosure of credit risk exposure [line items]  
Change in provision assuming 100bp decrease in GDP growth rate (as a percent) 2.60%
Change in provision assuming 100bp increase in GDP growth rate (as a percent) (1.40%)
Change in provision assuming 100bp decrease in unemployment rate (as a percent) (4.50%)
Change in provision assuming 100bp increase in unemployment rate (as a percent) 6.30%
Change in provision assuming 100bp decrease in interest rate (as a percent) (0.90%)
Change in provision assuming 100bp increase in interest rate (as a percent) 3.50%
SC Auto | Santander Consumer USA Holdings Inc. | US | Total North America  
Disclosure of credit risk exposure [line items]  
Change in provision assuming 100bp decrease in GDP growth rate (as a percent) 1.70%
Change in provision assuming 100bp increase in GDP growth rate (as a percent) (1.20%)
Change in provision assuming 100bp decrease in housing price change rate (as a percent) 3.10%
Change in provision assuming 100bp increase in housing price change rate (as a percent) (1.60%)
Change in provision assuming 100bp decrease in unemployment rate (as a percent) (4.90%)
Change in provision assuming 100bp increase in unemployment rate (as a percent) 7.00%
Change in provision assuming 100bp decrease in Manheim index (as a percent) 1.00%
Change in provision assuming 100bp increase in Manheim index (as a percent) (0.80%)