XML 192 R155.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Provisions - Summary of Changes in Provisions (Detail) - EUR (€) € in Millions | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016
Disclosure of other provisions [line items] |  |
Beginning balance | € 149 | € 163
Allowance | 25 | 13
Amounts used | (7) | (11)
Unused amounts reversed | (5) | (16)
Unwinding of discounts | (1) | 1
Reclassified to Pension liabilities |  | (3)
Effects of changes in foreign exchange rates | (8) | 2
Ending balance | 153 | 149
Current | 40 | 42
Non-Current | 113 | 107
Close down and environmental remediation costs [member] |  |
Disclosure of other provisions [line items] |  |
Beginning balance | 88 | 88
Allowance | 3 |
Amounts used | (2) | (2)
Unused amounts reversed |  | (1)
Unwinding of discounts | (1) | 1
Effects of changes in foreign exchange rates | (7) | 2
Ending balance | 81 | 88
Current | 4 | 3
Non-Current | 77 | 85
Restructuring costs [member] |  |
Disclosure of other provisions [line items] |  |
Beginning balance | 5 | 8
Allowance | 3 | 6
Amounts used | (2) | (5)
Unused amounts reversed | (1) | (1)
Reclassified to Pension liabilities |  | (3)
Ending balance | 5 | 5
Current | 3 | 3
Non-Current | 2 | 2
Legal claims and other costs [member] |  |
Disclosure of other provisions [line items] |  |
Beginning balance | 56 | 67
Allowance | 19 | 7
Amounts used | (3) | (4)
Unused amounts reversed | (4) | (14)
Effects of changes in foreign exchange rates | (1) |
Ending balance | 67 | 56
Current | 33 | 36
Non-Current | € 34 | € 20

X
- Definition Provision for reclassified to pension liabilities. + References No definition available. + Details
Name: | cstm_ProvisionForReclassifiedToPensionLiabilities
Namespace Prefix: | cstm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount of additional other provisions made. [Refer: Other provisions] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 37 -IssueDate 2017-01-01 -Paragraph 84 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=37&date=2017-03-01&anchor=para_84_b&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_AdditionalProvisionsOtherProvisions
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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_DisclosureOfOtherProvisionsLineItems
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The increase (decrease) in other provisions resulting from a change in discount rate. [Refer: Other provisions] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 37 -IssueDate 2017-01-01 -Paragraph 84 -Subparagraph e -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=37&date=2017-03-01&anchor=para_84_e&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_IncreaseDecreaseThroughChangeInDiscountRateOtherProvisions
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The increase (decrease) in other provisions resulting from foreign currency exchange rate changes on provisions measured in a currency different from the entity's presentation currency. [Refer: Other provisions] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 37 -IssueDate 2017-01-01 -Paragraph 84 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=37&date=2017-03-01&anchor=para_84&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_IncreaseDecreaseThroughNetExchangeDifferencesOtherProvisions
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount of non-current provisions other than provisions for employee benefits. [Refer: Non-current provisions] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 78 -Subparagraph d -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_78_d&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_OtherLongtermProvisions
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount of provisions other than provisions for employee benefits. [Refer: Provisions] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 37 -IssueDate 2017-01-01 -Paragraph 84 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=37&date=2017-03-01&anchor=para_84_a&doctype=Standard -URIDate 2017-03-09 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 78 -Subparagraph d -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_78_d&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_OtherProvisions
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount of current provisions other than provisions for employee benefits. [Refer: Provisions] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 78 -Subparagraph d -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_78_d&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_OtherShorttermProvisions
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount used (ie incurrent and charged against the provision) for other provisions. [Refer: Other provisions] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 37 -IssueDate 2017-01-01 -Paragraph 84 -Subparagraph c -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=37&date=2017-03-01&anchor=para_84_c&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_ProvisionUsedOtherProvisions
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The amount reversed for unused other provisions. [Refer: Other provisions] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 37 -IssueDate 2017-01-01 -Paragraph 84 -Subparagraph d -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=37&date=2017-03-01&anchor=para_84_d&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_UnusedProvisionReversedOtherProvisions
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | ifrs-full_ClassesOfProvisionsAxis=ifrs-full_ProvisionForDecommissioningRestorationAndRehabilitationCostsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_ClassesOfProvisionsAxis=ifrs-full_RestructuringProvisionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_ClassesOfProvisionsAxis=ifrs-full_LegalProceedingsProvisionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |