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Trade Receivables and Other - Additional Information (Detail) | 12 Months Ended
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Dec. 31, 2018 EUR (€) | Dec. 31, 2018 USD ($) | Dec. 31, 2017 EUR (€)
Disclosure of trade and other receivables [line items] |  |  |
Reversal of impairment allowance | € 1,100,000 |  | € 700,000
Factored assets | 601,000,000 |  | 642,000,000
Factored assets, derecognized from Consolidated Statement of Financial Position | 446,000,000 |  | 473,000,000
Factored assets, recognized in Consolidated Statement of Financial Position | 155,000,000 |  | 169,000,000
Debt due factor | € 0 |  | 0
Finance lease receivables |  |  | € 12,000,000
Factoring of receivables [member] | Muscle Shoals factoring facility [member] |  |  |
Disclosure of trade and other receivables [line items] |  |  |
Factoring maximum capacity | $ |  | $ 375,000,000 |
Trade receivable factoring agreement maturity date | Jan. 24, 2020 | Jan. 24, 2020 |
France [member] | Factoring of receivables [member] |  |  |
Disclosure of trade and other receivables [line items] |  |  |
Factoring maximum capacity | € 235,000,000 |  |
Trade receivable factoring agreement maturity date | Oct. 29, 2021 | Oct. 29, 2021 |
Germany Switzerland and Czech Republic [member] | Factoring of receivables [member] |  |  |
Disclosure of trade and other receivables [line items] |  |  |
Factoring maximum capacity | € 150,000,000 |  |
Trade receivable factoring agreement maturity date | Oct. 29, 2021 | Oct. 29, 2021 |
United States [member] | Factoring of receivables [member] | Constellium automotive [member] |  |  |
Disclosure of trade and other receivables [line items] |  |  |
Factoring maximum capacity | $ |  | $ 25,000,000 |
Trade receivable factoring agreement maturity date | Dec. 11, 2019 | Dec. 11, 2019 |
United States [member] | Factoring of receivables amendment [member] | Constellium automotive [member] |  |  |
Disclosure of trade and other receivables [line items] |  |  |
Factoring maximum capacity | $ |  | $ 33,000,000 |

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- Definition The amount of receivables related to finance leases. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2018-01-01 -Paragraph 55 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_55&doctype=Standard -URIDate 2018-03-16 + Details
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