XML 62 R54.htm IDEA: XBRL DOCUMENT
v3.20.2

GENERAL INFORMATION (Details) | Jun. 30, 2020 Employees Center Facility site
--- | ---
Disclosure of general information [abstract] |
Number of production facilities | Facility | 28
Number of administrative and commercial sites | site | 3
Number of R&D centers | Center | 3
Number of employees | Employees | 12,400

X
- Definition Disclosure of general information. + References No definition available. + Details
Name: | cstm_DisclosureOfGeneralInformationAbstract
Namespace Prefix: | cstm_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of administrative and commercial sites. + References No definition available. + Details
Name: | cstm_NumberOfAdministrativeAndCommercialSites
Namespace Prefix: | cstm_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of production facilities. + References No definition available. + Details
Name: | cstm_NumberOfProductionFacilities
Namespace Prefix: | cstm_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of world class technology center. + References No definition available. + Details
Name: | cstm_NumberOfWorldClassTechnologyCenter
Namespace Prefix: | cstm_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition The number of personnel employed by the entity at a date. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2019-01-01 -Paragraph 112 -Subparagraph c -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_112_c&doctype=Standard -URIDate 2019-03-27 + Details
Name: | ifrs-full_NumberOfEmployees
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant