Risk management - Schedule of exposure to risk, Spain residential mortgage (Details) - EUR (€) € in Millions	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Disclosure of credit risk exposure [line items]
Financial assets	€ 300,026	€ 283,497	€ 243,203
Spain \| Mortgages \| Gross carrying amount
Disclosure of credit risk exposure [line items]
Financial assets	60,002	59,316	61,097
Spain \| Mortgages \| Gross carrying amount \| Credit impaired
Disclosure of credit risk exposure [line items]
Financial assets	625	789	924
Spain \| Mortgages \| Gross carrying amount \| Without mortgage collateral
Disclosure of credit risk exposure [line items]
Financial assets	215	208	215
Spain \| Mortgages \| Gross carrying amount \| Without mortgage collateral \| Credit impaired
Disclosure of credit risk exposure [line items]
Financial assets	7	11	16
Spain \| Mortgages \| Gross carrying amount \| With mortgage collateral
Disclosure of credit risk exposure [line items]
Financial assets	59,787	59,108	60,882
Spain \| Mortgages \| Gross carrying amount \| With mortgage collateral \| Credit impaired
Disclosure of credit risk exposure [line items]
Financial assets	€ 618	€ 778	€ 908

The amount of assets that are: (a) cash; (b) an equity instrument of another entity; (c) a contractual right: (i) to receive cash or another financial asset from another entity; or (ii) to exchange financial assets or financial liabilities with another entity under conditions that are potentially favourable to the entity; or (d) a contract that will, or may be, settled in the entity’s own equity instruments and is: (i) a non-derivative for which the entity is, or may be, obliged to receive a variable number of the entity’s own equity instruments; or (ii) a derivative that will, or may be, settled other than by the exchange of a fixed amount of cash or another financial asset for a fixed number of the entity’s own equity instruments. For this purpose the entity’s own equity instruments do not include puttable financial instruments classified as equity instruments in accordance with paragraphs 16A-16B of IAS 32, instruments that impose on the entity an obligation to deliver to another party a pro rata share of the net assets of the entity only on liquidation and are classified as equity instruments in accordance with paragraphs 16C-16D of IAS 32, or instruments that are contracts for the future receipt or delivery of the entity’s own equity instruments. [Refer: Classes of financial instruments [domain]; Financial liabilities]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2025-01-01
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
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Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Name IFRS
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
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+ Details