Revenue - Disaggregation of revenue from contracts with customers (Details) - EUR (€) € in Thousands	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenue
Revenue	€ 108,622	€ 106,424	€ 60,938
Time charter services and transportation and installation services
Revenue
Revenue	99,841	104,578	56,449
Other revenue, including fees earned for early termination by customers of contracts
Revenue
Revenue	€ 8,781	€ 1,846	€ 4,489

The amount of revenue from contracts with customers. A customer is a party that has contracted with an entity to obtain goods or services that are an output of the entity’s ordinary activities in exchange for consideration.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 15
-IssueDate 2023-01-01
-Paragraph 114
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=15&code=ifrs-tx-2023-en-r&anchor=para_114&doctype=Standard
-URIDate 2023-03-23

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 15
-IssueDate 2023-01-01
-Paragraph 113
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=15&code=ifrs-tx-2023-en-r&anchor=para_113_a&doctype=Standard
-URIDate 2023-03-23

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