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Summary of Significant Accounting Policies - Additional Information (Detail) - EUR (€) € in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Jan. 01, 2019
Summary of significant accounting policies [line items] |  |  |  |
Loss allowance recognized in opening retained earnings net of tax | € 2 | € 0 |  |
Business combination description | Recognized assets and liabilities may be adjusted during a maximum of 12 months from the acquisition date, depending on new information obtained about the facts and circumstances existing at the acquisition date. |  |  |
Interest cost on pension and other benefits | € 15 | € 17 | € 21 |
Technology [member] |  |  |  |
Summary of significant accounting policies [line items] |  |  |  |
Intangible assets amortized estimated useful life | 20 years |  |  |
Customer relationships [member] |  |  |  |
Summary of significant accounting policies [line items] |  |  |  |
Intangible assets amortized estimated useful life | 25 years |  |  |
IFRS 16 [member] |  |  |  |
Summary of significant accounting policies [line items] |  |  |  |
Right-of-use assets expect to recognize |  |  |  | € 102
Lease liabilities expect to recognize |  |  |  | € 102
Bottom of range [member] | Computer software [member] |  |  |  |
Summary of significant accounting policies [line items] |  |  |  |
Intangible assets amortized estimated useful life | 3 years |  |  |
Bottom of range [member] | Buildings [member] |  |  |  |
Summary of significant accounting policies [line items] |  |  |  |
Property, plant and equipment, useful life | 10 years |  |  |
Bottom of range [member] | Machinery and equipment [member] |  |  |  |
Summary of significant accounting policies [line items] |  |  |  |
Property, plant and equipment, useful life | 3 years |  |  |
Bottom of range [member] | Vehicles [member] |  |  |  |
Summary of significant accounting policies [line items] |  |  |  |
Property, plant and equipment, useful life | 5 years |  |  |
Top of range [member] | Computer software [member] |  |  |  |
Summary of significant accounting policies [line items] |  |  |  |
Intangible assets amortized estimated useful life | 5 years |  |  |
Top of range [member] | Buildings [member] |  |  |  |
Summary of significant accounting policies [line items] |  |  |  |
Property, plant and equipment, useful life | 50 years |  |  |
Top of range [member] | Machinery and equipment [member] |  |  |  |
Summary of significant accounting policies [line items] |  |  |  |
Property, plant and equipment, useful life | 40 years |  |  |
Top of range [member] | Vehicles [member] |  |  |  |
Summary of significant accounting policies [line items] |  |  |  |
Property, plant and equipment, useful life | 8 years |  |  |

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