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Currency Gains / (Losses) - Summary of Currency Gains and Losses Included in Income from Operations (Detail) - EUR (€) € in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017
Analysis of income and expense [line items] |  |  |  |
Currency gains /(losses) | € 6 | € 3 | € 6 | € (5)
Realized exchange (losses) / gains on foreign currency derivatives - net | (1) | (1) | 1 | (11)
Unrealized gains on foreign currency derivatives - net | 4 | 7 | 3 | 13
Exchanges gains / (losses) from the remeasurement of monetary assets and liabilities - net | 3 | (3) | 2 | (7)
Revenue [member] |  |  |  |
Analysis of income and expense [line items] |  |  |  |
Currency gains /(losses) | 1 | 1 | 3 | (1)
Cost of sales [member] |  |  |  |
Analysis of income and expense [line items] |  |  |  |
Currency gains /(losses) | 2 | (2) |  | (2)
Other gains / (losses - net [member] |  |  |  |
Analysis of income and expense [line items] |  |  |  |
Currency gains /(losses) | € 3 | € 4 | € 3 | € (2)

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