Subordinated loans - Schedule of subordinated loans by group companies (Details) - EUR (€) € in Millions	Dec. 31, 2025	Dec. 31, 2024
Subordinated liabilities [abstract]
Subordinated loans	€ 18,100	€ 17,878

The amount of liabilities that are subordinate to other liabilities with respect to claims.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Note Expiry date 2027-01-01
-Name IAS
-Number 1
-IssueDate 2025-01-01
-Paragraph 55
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2025-en-b&anchor=para_55&doctype=Standard
-URIDate 2025-03-27

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