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Operating Segment Information - Summary of Segment adjusted EBITDA and reconciliation of Adjusted EBITDA to Net Income (Parenthetical) (Detail) - EUR (€) € in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017
Disclosure of segment adjusted EBITDA and reconciliation of adjusted EBITDA to net income [line items] |  |  |  |
Start-up costs and development cost | € (5) | € (5) | € (9) | € (10)
Gains / (Losses) on pension plan amendments |  |  |  | 22
AS&I [member] |  |  |  |
Disclosure of segment adjusted EBITDA and reconciliation of adjusted EBITDA to net income [line items] |  |  |  |
Start-up costs and development cost | 0 |  | 9 | 7
Automotive Body Sheet Growth Projects [member] |  |  |  |
Disclosure of segment adjusted EBITDA and reconciliation of adjusted EBITDA to net income [line items] |  |  |  |
Start-up costs and development cost | € 0 |  | € 0 | € 3

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- Definition Disclosure of segment adjusted EBITDA and reconciliation of adjusted EBITDA to net income. + References No definition available. + Details
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- Definition Gains (losses) on pension plan amendments. + References No definition available. + Details
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- Definition Startup and development costs. + References No definition available. + Details
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- Details
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- Details
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