Related Party Transactions - Transactions with Subsidiaries, Joint Ventures and Associates - Deposits (Detail) - EUR (€) € in Millions	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024
Related party transactions [abstract]
Deposits outstanding, beginning of year	€ 29	€ 33
Net movement in deposits during the period	(7)	(4)
Changes in the group of consolidated companies	0	0
Exchange rate changes/other	0	0
Deposits outstanding, end of year	€ 22	€ 29

The amounts payable resulting from related party transactions. [Refer: Total for all related parties [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 24
-IssueDate 2025-01-01
-Paragraph 20
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-URIDate 2025-03-27

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 24
-IssueDate 2025-01-01
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-Subparagraph b
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-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 230
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_230_b&doctype=Standard
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
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-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_230_b&doctype=Standard
-URIDate 2025-03-27

Name:	ifrs-full_AmountsPayableRelatedPartyTransactions
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant