Off-balance-sheet exposures - Narrative (Details) - EUR (€) € in Millions	Jun. 30, 2026	Dec. 31, 2025
Other assets \| Next 12 months
Disclosure of contingent liabilities [line items]
Exposure to credit risk on loan commitments	€ 471,257	€ 464,215
Other assets \| Next 12 months \| Contingent liabilities and commitments
Disclosure of contingent liabilities [line items]
Other provisions	357	338
Other assets \| Lifetime expected credit losses
Disclosure of contingent liabilities [line items]
Exposure to credit risk on loan commitments	21,854	21,241
Other assets \| Lifetime expected credit losses \| Contingent liabilities and commitments
Disclosure of contingent liabilities [line items]
Other provisions	218	206
Impaired assets \| Lifetime expected credit losses
Disclosure of contingent liabilities [line items]
Exposure to credit risk on loan commitments	1,322	1,345
Impaired assets \| Lifetime expected credit losses \| Contingent liabilities and commitments
Disclosure of contingent liabilities [line items]
Other provisions	€ 173	€ 169

The amount of the exposure to credit risk on loan commitments and financial guarantee contracts. [Refer: Loan commitments [member]; Financial guarantee contracts [member]; Credit risk [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
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-IssueDate 2025-01-01
-Paragraph 66
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_66&doctype=Standard
-URIDate 2025-03-27

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
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-Paragraph 71
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_71&doctype=Standard
-URIDate 2025-03-27

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph 70
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_70&doctype=Standard
-URIDate 2025-03-27

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2025-01-01
-Paragraph 35H
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2025-en-r&anchor=para_35H&doctype=Standard
-URIDate 2025-03-27

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
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-Paragraph 35M
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2025-en-r&anchor=para_35M&doctype=Standard
-URIDate 2025-03-27

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
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-Paragraph 35I
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2025-en-r&anchor=para_35I&doctype=Standard
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph 70
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_70&doctype=Standard
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph 66
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_66&doctype=Standard
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph 71
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_71&doctype=Standard
-URIDate 2025-03-27

+ Details