XML 73 R66.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Finance Costs-Net - Summary of Finance Costs - Net (Detail) - EUR (€) € in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017
Analysis of income and expense [abstract] |  |  |  |
Interest received | € 1 | € 2 | € 3 | € 3
Finance income | 1 | 2 | 3 | 3
Interest expense on borrowings paid or payable | (30) | (38) | (58) | (79)
Expenses on factoring arrangements paid or payable | (5) | (4) | (9) | (8)
Net loss on settlement of debt |  |  |  | (13)
Realized and unrealized gains / (losses) on debt derivatives at fair value | 23 | (47) | 16 | (55)
Realized and unrealized exchange (losses) / gains on financing activities-net | (22) | 52 | (11) | 63
Other finance expense | (3) | (6) | (13) | (8)
Capitalized borrowing costs |  | 2 | 2 | 4
Finance expense | (37) | (41) | (73) | (96)
Finance costs - net | € (36) | € (39) | € (70) | € (93)

X
- Definition Borrowing costs capitalised credit. + References No definition available. + Details
Name: | cstm_BorrowingCostsCapitalisedCredit
Namespace Prefix: | cstm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Expenses on factoring arrangements paid or payable. + References No definition available. + Details
Name: | cstm_ExpensesOnFactoringArrangementsPaidOrPayable
Namespace Prefix: | cstm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Realized and Unrealized Exchange Gains (Losses) on Financing Activities - Net + References No definition available. + Details
Name: | cstm_RealizedAndUnrealizedExchangeGainsLossesOnFinancingActivitiesNet
Namespace Prefix: | cstm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- References No definition available. + Details
Name: | ifrs-full_AnalysisOfIncomeAndExpenseAbstract
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of costs associated with financing activities of the entity. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 82 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_82_b&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_FinanceCosts
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The amount of income associated with interest and other financing activities of the entity. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 85 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_85&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_FinanceIncome
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount of income or cost associated with interest and other financing activities of the entity. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 85 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_85&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_FinanceIncomeCost
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The gain (loss) arising from the difference between the carrying amount of the financial liability extinguished and the measurement of the consideration paid (equity instruments issued) to the creditor. [Refer: Carrying amount [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRIC -Number 19 -IssueDate 2017-01-01 -Paragraph 11 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRIC&num=19&date=2017-03-01&anchor=para_11&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_GainLossArisingFromDifferenceBetweenCarryingAmountOfFinancialLiabilityExtinguishedAndConsiderationPaid
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The gains (losses) resulting from change in the fair value of derivatives recognised in profit or loss. [Refer: Derivatives [member]] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 85 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_85&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_GainsLossesOnChangeInFairValueOfDerivatives
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount of interest expense on borrowings. [Refer: Interest expense; Borrowings] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 112 -Subparagraph c -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_112_c&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_InterestExpenseOnBorrowings
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The amount of finance income or cost that the entity does not separately disclose in the same statement or note. [Refer: Finance income (cost)] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 85 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_85&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_OtherFinanceIncomeCost
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount of income arising from interest. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 8 -IssueDate 2017-01-01 -Paragraph 23 -Subparagraph c -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=8&date=2017-03-01&anchor=para_23_c&doctype=Standard -URIDate 2017-03-09 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 8 -IssueDate 2017-01-01 -Paragraph 28 -Subparagraph e -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=8&date=2017-03-01&anchor=para_28_e&doctype=Standard -URIDate 2017-03-09 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Note Expiry date 2018-01-01 -Name IAS -Number 18 -IssueDate 2017-01-01 -Paragraph 35 -Subparagraph b -Clause iii -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=18&date=2017-03-02&anchor=para_35_b_iii&doctype=Standard&book=B -URIDate 2017-03-09 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 12 -IssueDate 2017-01-01 -Paragraph B13 -Subparagraph e -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=12&date=2017-03-01&anchor=para_B13_e&doctype=Appendix&seq=2 -URIDate 2017-03-09 Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 112 -Subparagraph c -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_112_c&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_RevenueFromInterest
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration