Operating expenses - Selling, General and Administrative, Additional Information (Details) - EUR (€) € in Millions |
12 Months Ended | |
|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
|
| Disclosure Of Operating Expenses [Line Items] | ||
| Advisory fees | € 1.4 | |
| Janssen | ||
| Disclosure Of Operating Expenses [Line Items] | ||
| Legal fees | 0.5 | |
| Selling, general and administrative expense | ||
| Disclosure Of Operating Expenses [Line Items] | ||
| Increase (decrease) in rent, fees, and other expenses | € 0.1 | € 1.8 |
| Increase (decrease) in rent, fees, and other expenses, percentage | (1.00%) | 18.40% |