| Laufende Projekte [Achse] | de | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Construction contracts [axis] | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Projets en cours [axe] | fr | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Onderhanden projecten [as] | nl | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Laufende Projekte | de | http://www.xbrl.org/2003/role/terseLabel | http://www.xbrl.org/2003/role/link |
| Construction contracts | en | http://www.xbrl.org/2003/role/terseLabel | http://www.xbrl.org/2003/role/link |
| Projets en cours | fr | http://www.xbrl.org/2003/role/terseLabel | http://www.xbrl.org/2003/role/link |
| Onderhanden projecten | nl | http://www.xbrl.org/2003/role/terseLabel | http://www.xbrl.org/2003/role/link |