Financial instruments - Fair values and risk management - Guarantees (Details) - EUR (€) € in Millions	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2022
Subsidiaries \| Letters of guarantee
Disclosure of transactions between related parties [line items]
Letters of guarantee	€ 2,760	€ 4,120	€ 5,090

The amount that best represents the maximum exposure to credit risk without taking into account any collateral held or other credit enhancements (for example, netting agreements that do not qualify for offset in accordance with IAS 32). [Refer: Credit risk [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2023-01-01
-Paragraph 35K
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2023-en-r&anchor=para_35K_a&doctype=Standard
-URIDate 2023-03-23

Name:	ifrs-full_MaximumExposureToCreditRisk
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant