Income Tax - Additional Information (Details) - EUR (€) € in Thousands	12 Months Ended
Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Income Tax [Line items]
Applicable tax rate	25.00%	25.00%	25.00%
Deferred tax income	€ 20,599	€ 23,814	€ 27,781
Cumulative earnings	765,905	417,578
Subsidiaries
Income Tax [Line items]
Cumulative earnings	€ 704,000	€ 597,500
Jersey
Income Tax [Line items]
Applicable tax rate	0.00%	0.00%	0.00%
German
Income Tax [Line items]
Deferred tax income	€ 11,600

The amount of tax expense (income) relating to changes in deferred tax liabilities and deferred tax assets. [Refer: Deferred tax assets; Deferred tax liabilities]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 12
-IssueDate 2025-01-01
-Paragraph 81
-Subparagraph g
-Clause ii
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=12&code=ifrs-tx-2025-en-r&anchor=para_81_g_ii&doctype=Standard
-URIDate 2025-03-27

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph 194
-Subparagraph f
-Clause ii
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_194_f_ii&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 194
-Subparagraph f
-Clause ii
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_194_f_ii&doctype=Standard
-URIDate 2025-03-27

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration