XML 155 R113.htm IDEA: XBRL DOCUMENT
v3.19.1

Property Plant and Equipment - Summary of Amounts Included in Building, Machinery and Equipment Under a Finance Lease (Detail) - EUR (€) € in Millions | Dec. 31, 2018 | Dec. 31, 2017
--- | --- | ---
Disclosure of detailed information about property, plant and equipment [line items] |  |
Amounts included in Building/Machinery and Equipment under finance lease net | € 77 | € 60
Buildings [member] |  |
Disclosure of detailed information about property, plant and equipment [line items] |  |
Amounts included in Building/Machinery and Equipment under finance lease net | 24 | 25
Machinery and equipment [member] |  |
Disclosure of detailed information about property, plant and equipment [line items] |  |
Amounts included in Building/Machinery and Equipment under finance lease net | 53 | 35
Gross value [member] |  |
Disclosure of detailed information about property, plant and equipment [line items] |  |
Amounts included in Building/Machinery and Equipment under finance lease net | 110 | 92
Gross value [member] | Buildings [member] |  |
Disclosure of detailed information about property, plant and equipment [line items] |  |
Amounts included in Building/Machinery and Equipment under finance lease net | 31 | 30
Gross value [member] | Machinery and equipment [member] |  |
Disclosure of detailed information about property, plant and equipment [line items] |  |
Amounts included in Building/Machinery and Equipment under finance lease net | 79 | 62
Accumulated depreciation [member] |  |
Disclosure of detailed information about property, plant and equipment [line items] |  |
Amounts included in Building/Machinery and Equipment under finance lease net | (33) | (32)
Accumulated depreciation [member] | Buildings [member] |  |
Disclosure of detailed information about property, plant and equipment [line items] |  |
Amounts included in Building/Machinery and Equipment under finance lease net | (7) | (5)
Accumulated depreciation [member] | Machinery and equipment [member] |  |
Disclosure of detailed information about property, plant and equipment [line items] |  |
Amounts included in Building/Machinery and Equipment under finance lease net | € (26) | € (27)

X
- Definition Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table. + References No definition available. + Details
Name: | ifrs-full_DisclosureOfPropertyPlantAndEquipmentLineItems
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of assets recognised by the entity, which are leased under finance leases. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Note Expiry date 2019-01-01 -Name IAS -Number 17 -IssueDate 2018-01-01 -Paragraph 31 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=17&date=2018-03-02&anchor=para_31_a&doctype=Standard&book=b -URIDate 2018-03-16 + Details
Name: | ifrs-full_RecognisedFinanceLeaseAsAssets
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis=ifrs-full_BuildingsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis=cstm_MachineryAndEquipment1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis=ifrs-full_GrossCarryingAmountMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis=ifrs-full_AccumulatedDepreciationAndAmortisationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |