v3.26.1
Risk management - Schedule of exposure to risk, sovereign risk and exposure to other public sector entities (Details) - EUR (€)
€ in Millions
Dec. 31, 2025
Dec. 31, 2024
Spain    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic € 305,156  
Sovereign risk    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 224,947 € 198,627
Sovereign risk | Financial assets held for trading and Financial assets designated as FV with changes in results    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 38,785  
Sovereign risk | Financial assets at fair value through other comprehensive income    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 35,187  
Sovereign risk | Financial assets at amortized cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 150,975  
Sovereign risk | Non-trading financial assets mandatorily at fair value through profit or loss    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 0  
Sovereign risk | Spain    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 62,008 56,293
Sovereign risk | Spain | Financial assets held for trading and Financial assets designated as FV with changes in results    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 3,852  
Sovereign risk | Spain | Financial assets at fair value through other comprehensive income    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 112  
Sovereign risk | Spain | Financial assets at amortized cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 58,044  
Sovereign risk | Spain | Non-trading financial assets mandatorily at fair value through profit or loss    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 0  
Sovereign risk | Portugal    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 7,307 7,652
Sovereign risk | Portugal | Financial assets held for trading and Financial assets designated as FV with changes in results    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic (659)  
Sovereign risk | Portugal | Financial assets at fair value through other comprehensive income    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 1,199  
Sovereign risk | Portugal | Financial assets at amortized cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 6,767  
Sovereign risk | Portugal | Non-trading financial assets mandatorily at fair value through profit or loss    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 0  
Sovereign risk | Italy    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 15,872 12,915
Sovereign risk | Italy | Financial assets held for trading and Financial assets designated as FV with changes in results    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 2,875  
Sovereign risk | Italy | Financial assets at fair value through other comprehensive income    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 440  
Sovereign risk | Italy | Financial assets at amortized cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 12,557  
Sovereign risk | Italy | Non-trading financial assets mandatorily at fair value through profit or loss    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 0  
Sovereign risk | Greece    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 0 0
Sovereign risk | Greece | Financial assets held for trading and Financial assets designated as FV with changes in results    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 0  
Sovereign risk | Greece | Financial assets at fair value through other comprehensive income    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 0  
Sovereign risk | Greece | Financial assets at amortized cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 0  
Sovereign risk | Greece | Non-trading financial assets mandatorily at fair value through profit or loss    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 0  
Sovereign risk | Ireland    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic (38) 0
Sovereign risk | Ireland | Financial assets held for trading and Financial assets designated as FV with changes in results    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic (38)  
Sovereign risk | Ireland | Financial assets at fair value through other comprehensive income    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 0  
Sovereign risk | Ireland | Financial assets at amortized cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 0  
Sovereign risk | Ireland | Non-trading financial assets mandatorily at fair value through profit or loss    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 0  
Sovereign risk | Rest Eurozone    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 14,381 6,212
Sovereign risk | Rest Eurozone | Financial assets held for trading and Financial assets designated as FV with changes in results    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 3,684  
Sovereign risk | Rest Eurozone | Financial assets at fair value through other comprehensive income    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 254  
Sovereign risk | Rest Eurozone | Financial assets at amortized cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 10,443  
Sovereign risk | Rest Eurozone | Non-trading financial assets mandatorily at fair value through profit or loss    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 0  
Sovereign risk | United Kingdom    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 7,595 8,772
Sovereign risk | United Kingdom | Financial assets held for trading and Financial assets designated as FV with changes in results    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 907  
Sovereign risk | United Kingdom | Financial assets at fair value through other comprehensive income    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 1,001  
Sovereign risk | United Kingdom | Financial assets at amortized cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 5,687  
Sovereign risk | United Kingdom | Non-trading financial assets mandatorily at fair value through profit or loss    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 0  
Sovereign risk | Poland    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 20,813 14,286
Sovereign risk | Poland | Financial assets held for trading and Financial assets designated as FV with changes in results    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 1,141  
Sovereign risk | Poland | Financial assets at fair value through other comprehensive income    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 6,339  
Sovereign risk | Poland | Financial assets at amortized cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 13,333  
Sovereign risk | Poland | Non-trading financial assets mandatorily at fair value through profit or loss    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 0  
Sovereign risk | Rest of Europe    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 534 954
Sovereign risk | Rest of Europe | Financial assets held for trading and Financial assets designated as FV with changes in results    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 8  
Sovereign risk | Rest of Europe | Financial assets at fair value through other comprehensive income    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 0  
Sovereign risk | Rest of Europe | Financial assets at amortized cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 526  
Sovereign risk | Rest of Europe | Non-trading financial assets mandatorily at fair value through profit or loss    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 0  
Sovereign risk | United States    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 25,046 24,926
Sovereign risk | United States | Financial assets held for trading and Financial assets designated as FV with changes in results    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 4,783  
Sovereign risk | United States | Financial assets at fair value through other comprehensive income    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 4,320  
Sovereign risk | United States | Financial assets at amortized cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 15,943  
Sovereign risk | United States | Non-trading financial assets mandatorily at fair value through profit or loss    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 0  
Sovereign risk | Brazil    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 26,165 26,641
Sovereign risk | Brazil | Financial assets held for trading and Financial assets designated as FV with changes in results    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 8,089  
Sovereign risk | Brazil | Financial assets at fair value through other comprehensive income    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 9,533  
Sovereign risk | Brazil | Financial assets at amortized cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 8,543  
Sovereign risk | Brazil | Non-trading financial assets mandatorily at fair value through profit or loss    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 0  
Sovereign risk | Mexico    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 25,914 21,642
Sovereign risk | Mexico | Financial assets held for trading and Financial assets designated as FV with changes in results    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 10,663  
Sovereign risk | Mexico | Financial assets at fair value through other comprehensive income    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 7,652  
Sovereign risk | Mexico | Financial assets at amortized cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 7,599  
Sovereign risk | Mexico | Non-trading financial assets mandatorily at fair value through profit or loss    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 0  
Sovereign risk | Chile    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 8,596 6,900
Sovereign risk | Chile | Financial assets held for trading and Financial assets designated as FV with changes in results    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 676  
Sovereign risk | Chile | Financial assets at fair value through other comprehensive income    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 2,666  
Sovereign risk | Chile | Financial assets at amortized cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 5,254  
Sovereign risk | Chile | Non-trading financial assets mandatorily at fair value through profit or loss    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 0  
Sovereign risk | Rest of America    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 6,398 4,431
Sovereign risk | Rest of America | Financial assets held for trading and Financial assets designated as FV with changes in results    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 2,593  
Sovereign risk | Rest of America | Financial assets at fair value through other comprehensive income    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 1,654  
Sovereign risk | Rest of America | Financial assets at amortized cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 2,151  
Sovereign risk | Rest of America | Non-trading financial assets mandatorily at fair value through profit or loss    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 0  
Sovereign risk | Rest of the world    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 4,356 € 7,003
Sovereign risk | Rest of the world | Financial assets held for trading and Financial assets designated as FV with changes in results    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 211  
Sovereign risk | Rest of the world | Financial assets at fair value through other comprehensive income    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 17  
Sovereign risk | Rest of the world | Financial assets at amortized cost    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic 4,128  
Sovereign risk | Rest of the world | Non-trading financial assets mandatorily at fair value through profit or loss    
Disclosure of nature and extent of risks arising from financial instruments [line items]    
Risk exposure associated with instruments sharing characteristic € 0