v3.26.1
Hedging derivatives - Schedule of movement in hedging components in other comprehensive income (Details) - EUR (€)
€ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Disclosure of detailed information about hedged items [line items]      
Balance at beginning of year € (8,300) € (9,424) € (9,187)
Balance at end of year (7,445) (8,300) (9,424)
Cash flow hedges      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 1,049 558 2,592
Cash flow hedges | Interest rate risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 1,155 163 2,179
Cash flow hedges | Currency risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income (229) 312 7
Cash flow hedges | Interest rate and exchange rate risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 8 155 164
Cash flow hedges | Inflation risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 131 (70) 233
Gain or loss in value - recognized in equity 211 (139) 105
Amounts transferred to income statements (80) 69 128
Cash flow hedges | Equity risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income (16) (2) 9
Hedges of net investments in foreign operations      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 136 420 (1,888)
Minorities, taxes and others (330) 146 (941)
Hedges of net investments in foreign operations | Currency risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 136 420 (1,888)
Fair value hedges      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 0 0 0
Fair value hedges | Interest rate risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 0 0 0
Fair value hedges | Currency risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 0 0 0
Fair value hedges | Interest rate and exchange rate risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 0 0 0
A) Not designated elements - linked to a time period | Cash flow hedges | Interest rate risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income (19) 0 0
Gain or loss in value - recognized in equity (19) 0 0
Amounts transferred to income statements 0 0 0
Other reclassifications 0 0 0
A) Not designated elements - linked to a time period | Cash flow hedges | Currency risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 11 0 0
Gain or loss in value - recognized in equity 26 0 0
Amounts transferred to income statements (15) 0 0
Other reclassifications 0 0 0
A) Not designated elements - linked to a time period | Cash flow hedges | Interest rate and exchange rate risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 0 0 0
A) Not designated elements - linked to a time period | Cash flow hedges | Equity risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income (6) 0 0
Gain or loss in value - recognized in equity (8) 0 0
Amounts transferred to income statements 2 0 0
Other reclassifications 0 0 0
A) Not designated elements - linked to a time period | Hedges of net investments in foreign operations | Currency risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 0 0 0
A) Not designated elements - linked to a time period | Fair value hedges | Interest rate risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 0 0 0
A) Not designated elements - linked to a time period | Fair value hedges | Currency risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 0 0 0
A) Not designated elements - linked to a time period | Fair value hedges | Interest rate and exchange rate risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 0 0 0
B) Not designated elements - linked to a transaction | Cash flow hedges | Interest rate risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 0 0 0
B) Not designated elements - linked to a transaction | Cash flow hedges | Currency risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 0 0 0
B) Not designated elements - linked to a transaction | Cash flow hedges | Interest rate and exchange rate risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 0 0 0
B) Not designated elements - linked to a transaction | Cash flow hedges | Equity risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 0 0 0
B) Not designated elements - linked to a transaction | Hedges of net investments in foreign operations | Currency risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 0 0 0
B) Not designated elements - linked to a transaction | Fair value hedges | Interest rate risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 0 0 0
B) Not designated elements - linked to a transaction | Fair value hedges | Currency risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 0 0 0
B) Not designated elements - linked to a transaction | Fair value hedges | Interest rate and exchange rate risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 0 0 0
C) Designated elements      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 1,199 978 704
Amounts transferred to income statements 706 1,256 2,622
C) Designated elements | Cash flow hedges      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 1,063 558 2,592
Amounts transferred to income statements 706 1,256 2,622
C) Designated elements | Cash flow hedges | Interest rate risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 1,174 163 2,179
Gain or loss in value - recognized in equity 536 (1,003) 532
Amounts transferred to income statements 638 1,166 1,647
C) Designated elements | Cash flow hedges | Currency risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income (240) 312 7
Gain or loss in value - recognized in equity (155) 631 (409)
Amounts transferred to income statements (85) (319) 416
C) Designated elements | Cash flow hedges | Interest rate and exchange rate risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 8 155 164
Gain or loss in value - recognized in equity (225) (185) 267
Amounts transferred to income statements 233 340 431
C) Designated elements | Cash flow hedges | Inflation risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 131 (70) 233
Amounts transferred to income statements (80) 69 128
C) Designated elements | Cash flow hedges | Equity risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income (10) (2) 9
Gain or loss in value - recognized in equity (10) (2) 9
Amounts transferred to income statements 0 0 0
C) Designated elements | Hedges of net investments in foreign operations      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 136 420 (1,888)
Amounts transferred to income statements 0 0 0
C) Designated elements | Hedges of net investments in foreign operations | Currency risk      
Disclosure of detailed information about hedged items [line items]      
Earnings (losses) recognized in other comprehensive income 136 420 (1,888)
Gain or loss in value - recognized in equity 136 420 (1,888)
Amounts transferred to income statements € 0 € 0 € 0