Other financial assets - Schedule of Changes in the Fair Value of Financial Assets at FVTPL (Detail) - EUR (€) € in Millions	Dec. 31, 2025	Dec. 31, 2024
Disclosure Of Other financial assets measured at fair value through profit or loss [Abstract]
Financial assets measured at FVTPL listed equity securities	€ 2	€ 1
Financial assets measured at FVTPL other equity securities	91	19
Financial assets measured at FVTPL debt securities	19	0
Financial assets measured at FVTPL collateral	8	0
Financial assets measured at FVTPL other financial assets	9	14
Financial assets measured at FVTPL	129	34
Financial Assets At Amortised Cost [Abstract]
Other financial assets	15	0
Total other financial assets	144	34
Non-current	135	34
Current	€ 9	€ 0

The amount of current financial assets measured at amortised cost. [Refer: Financial assets at amortised cost]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2025-01-01
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-URIDate 2025-03-27

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
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-IssueDate 2025-01-01
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
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-IssueDate 2025-01-01
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The amount of financial assets at amortised cost. The amortised cost is the amount at which financial assets are measured at initial recognition minus principal repayments, plus or minus the cumulative amortisation using the effective interest method of any difference between that initial amount and the maturity amount, and adjusted for any impairment. [Refer: Financial assets]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph 44
-Subparagraph c
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_44_c&doctype=Standard
-URIDate 2025-03-27

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2025-01-01
-Paragraph 8
-Subparagraph f
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2025-en-r&anchor=para_8_f&doctype=Standard
-URIDate 2025-03-27

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
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-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_44_c&doctype=Standard
-URIDate 2025-03-27

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The amount of non-current financial assets measured at amortised cost. [Refer: Financial assets at amortised cost]

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Financial assets at amortised cost.

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Financial assets at fair value through profit or loss as collateral.

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Financial assets measured at FVTPL.

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Financial assets measured at FVTPL listed debt securities.

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Financial assets measured at FVTPL listed equity securities.

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Financial assets measured at FVTPL listed other equity securities.

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Financial assets measured at FVTPL listed other financial assets.

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Other financial assets at amortised cost.

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