v3.26.1
Note 21 Debt certificates (Details) - EUR (€)
€ in Millions
Jun. 30, 2026
Dec. 31, 2025
Issued in Euros    
Debt certificates issued [Line Items]    
Debt Securities at amortized cost € 50,799 € 42,070
Issued in Euros | Promissory bills and notes [Member]    
Debt certificates issued [Line Items]    
Debt Securities at amortized cost 6,481 5,379
Issued in Euros | Non convertible bonds and debentures [Member]    
Debt certificates issued [Line Items]    
Debt Securities at amortized cost 17,211 15,860
Issued in Euros | Covered bonds [Member]    
Debt certificates issued [Line Items]    
Debt Securities at amortized cost 5,642 3,371
Issued in Euros | Hybrid financial instruments [Member]    
Debt certificates issued [Line Items]    
Debt Securities at amortized cost [1] 1,614 1,160
Issued in Euros | Securilization bonds [Member]    
Debt certificates issued [Line Items]    
Debt Securities at amortized cost 4,544 3,203
Issued in Euros | Wholesale funding [Member]    
Debt certificates issued [Line Items]    
Debt Securities at amortized cost 6,949 3,688
Issued in Euros | Subordinated liabilities [Member]    
Debt certificates issued [Line Items]    
Debt Securities at amortized cost 8,358 9,409
Issued in Euros | Convertible perpetual certificates [Member]    
Debt certificates issued [Line Items]    
Debt Securities at amortized cost 2,750 3,750
Issued in Euros | Other non convertible subordinated liabilities [Member]    
Debt certificates issued [Line Items]    
Debt Securities at amortized cost 5,608 5,659
Other exchanges [Member]    
Debt certificates issued [Line Items]    
Debt Securities at amortized cost 55,356 39,773
Other exchanges [Member] | Promissory bills and notes [Member]    
Debt certificates issued [Line Items]    
Debt Securities at amortized cost 6,290 2,781
Other exchanges [Member] | Non convertible bonds and debentures [Member]    
Debt certificates issued [Line Items]    
Debt Securities at amortized cost 18,457 13,302
Other exchanges [Member] | Covered bonds [Member]    
Debt certificates issued [Line Items]    
Debt Securities at amortized cost 101 94
Other exchanges [Member] | Hybrid financial instruments [Member]    
Debt certificates issued [Line Items]    
Debt Securities at amortized cost 10,524 7,914
Other exchanges [Member] | Wholesale funding [Member]    
Debt certificates issued [Line Items]    
Debt Securities at amortized cost 7,205 4,142
Other exchanges [Member] | Subordinated liabilities [Member]    
Debt certificates issued [Line Items]    
Debt Securities at amortized cost 12,778 11,540
Other exchanges [Member] | Convertible perpetual certificates [Member]    
Debt certificates issued [Line Items]    
Debt Securities at amortized cost 3,511 2,553
Other exchanges [Member] | Other non convertible subordinated liabilities [Member]    
Debt certificates issued [Line Items]    
Debt Securities at amortized cost € 9,267 € 8,986
[1] 1) Corresponds to structured note issuances with embedded derivatives that have been segregated according to IFRS 9.