Financial Instruments and Financial Risk Management - Schedule of Fair Value and Fair Value Hierarchy of Tax Receivable Liability Carried at Amortized Cost (Details) - EUR (€) € in Thousands |
Mar. 31, 2026 |
Sep. 30, 2025 |
|---|---|---|
| Disclosure of fair value measurement of liabilities [line items] | ||
| Tax receivable agreement liability | € 294,219 | € 302,400 |
| Carrying Value | Level 3 | ||
| Disclosure of fair value measurement of liabilities [line items] | ||
| Tax receivable agreement liability | 355,100 | 356,764 |
| Fair Value | Level 3 | ||
| Disclosure of fair value measurement of liabilities [line items] | ||
| Tax receivable agreement liability | € 387,472 | € 370,080 |