XML 143 R106.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Property Plant and Equipment - Summary of Amounts Included in Building, Machinery and Equipment Under a Finance Lease (Detail) - EUR (€) € in Millions | Dec. 31, 2017 | Dec. 31, 2016
--- | --- | ---
Disclosure of detailed information about property, plant and equipment [line items] |  |
Amounts included in Building/Machinery and Equipment under finance lease net | € 60 | € 57
Buildings [member] |  |
Disclosure of detailed information about property, plant and equipment [line items] |  |
Amounts included in Building/Machinery and Equipment under finance lease net | 25 | 28
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 | 35 | 29
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 | 92 | 81
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 | 30 | 31
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 | 62 | 50
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 | (32) | (24)
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 | (5) | (3)
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 | € (27) | € (21)

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 2017-01-01 -Paragraph 31 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=17&date=2017-03-02&anchor=para_31_a&doctype=Standard&book=B -URIDate 2017-03-09 + 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: |