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Currency Gains / (Losses) - Summary of Currency Gains and Losses Included in Income from Operations (Detail) - EUR (€) € in Millions | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Analysis of income and expense [line items] |  |  |
Currency gains /(losses) | € 11 | € (6) | € 1
Realized exchange gains / (losses) on foreign currency derivatives-net | 11 | (15) | (46)
Unrealized (losses) / gains on foreign currency derivatives-net | (3) | 17 | 40
Exchange gains / (losses) from the remeasurement of monetary assets and liabilities-net | 3 | (8) | 7
Revenue [member] |  |  |
Analysis of income and expense [line items] |  |  |
Currency gains /(losses) | 2 | 2 |
Cost of sales [member] |  |  |
Analysis of income and expense [line items] |  |  |
Currency gains /(losses) | 2 | (4) | 4
Other gains / (losses - net [member] |  |  |
Analysis of income and expense [line items] |  |  |
Currency gains /(losses) | € 7 | € (4) | € (3)

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