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Acquisition of Constellium-Bowling Green - Additional Information (Detail) - EUR (€) € in Millions | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2018 | Jan. 10, 2019 | Dec. 31, 2017
Disclosure of detailed information about business combination [line items] |  |  |
Preexisting trade receivables with acquiree | € 481 |  | € 306
Constellium-Bowling Green [member] |  |  |
Disclosure of detailed information about business combination [line items] |  |  |
Combined revenue | 5,772 |  |
Combined net income | € 159 |  |
Constellium-Bowling Green [member] | Major business combination [member] |  |  |
Disclosure of detailed information about business combination [line items] |  |  |
Percentage of voting equity interests acquired |  | 49.00% |
Consideration transferred |  | € 87 |
Fair value of previously held interest |  | 73 |
Preexisting trade receivables with acquiree |  | € 38 |

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