Employee benefits - Additional Information (Details) € in Thousands	1 Months Ended	12 Months Ended
Apr. 30, 2023 item	Dec. 31, 2023 EUR (€)	Dec. 31, 2022 EUR (€)	Dec. 31, 2021 EUR (€)
Employee benefits
Employer's contributions to pension insurance plans \| €		€ 1,272	€ 1,322	€ 1,030
Number of clinical stage development programs \| item	3

The amount of employer contributions to retirement benefit plans.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 26
-IssueDate 2023-01-01
-Paragraph 35
-Subparagraph b
-Clause i
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=26&code=ifrs-tx-2023-en-r&anchor=para_35_b_i&doctype=Standard
-URIDate 2023-03-23

Name:	ifrs-full_EmployerContributions
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration