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Borrowings - Summary of Reconciliation of Movement in Net Borrowings Explanatory (Parenthetical) (Detail) € in Millions |  |  | 12 Months Ended |
--- | --- | --- | --- | ---
Nov. 09, 2017 EUR (€) EUR_per_USD | Feb. 16, 2017 EUR (€) EUR_per_USD | Dec. 31, 2017 EUR (€) | Dec. 31, 2016 EUR (€) | Dec. 05, 2016 EUR (€) EUR_per_USD
Disclosure of detailed information about borrowings [line items] |  |  |  |  |
Proceeds from the issuance of senior notes |  |  | € 1,440 | € 375 |
Redemption of senior notes |  |  | € 1,559 | € 148 |
Constellium N.V. USD Senior Unsecured Notes (Issued November 2017, due 2026) [member] |  |  |  |  |
Disclosure of detailed information about borrowings [line items] |  |  |  |  |
Proceeds from the issuance of senior notes | € 830 |  |  |  |
Exchange rate | EUR_per_USD | 1.1630 |  |  |  |
Constellium N.V. Senior Unsecured Notes (Issued February 2017, due 2025) [member] |  |  |  |  |
Disclosure of detailed information about borrowings [line items] |  |  |  |  |
Proceeds from the issuance of senior notes |  | € 610 |  |  |
Exchange rate | EUR_per_USD |  | 1.0652 |  |  |
Senior secured and unsecured notes [member] |  |  |  |  |
Disclosure of detailed information about borrowings [line items] |  |  |  |  |
Redemption of senior notes | € 949 |  |  |  |
Exchange rate | EUR_per_USD | 1.1630 |  |  |  |
Muscle Shoals senior unsecured PIK toggle notes [member] |  |  |  |  |
Disclosure of detailed information about borrowings [line items] |  |  |  |  |
Redemption on PIK Toggle notes |  |  |  |  | € 148
Exchange rate | EUR_per_USD |  |  |  |  | 1.0702

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- Definition The spot exchange rate at the end of the reporting period. Exchange rate is the ratio of exchange for two currencies. Spot exchange rate is the exchange rate for immediate delivery. + 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
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