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Operating Segment Information - Additional Information (Detail) € in Millions | 12 Months Ended
--- | ---
Dec. 31, 2017 EUR (€) Employees Facility | Dec. 31, 2016 EUR (€) | Dec. 31, 2015 EUR (€)
Disclosure of operating segments [line items] |  |  |
Number of employees | 12,000 |  |
Information about major customers | No other single customer contributed 10% or more to the Group's revenue for 2017, 2016 and 2015. |  |
P&ARP [member] |  |  |
Disclosure of operating segments [line items] |  |  |
Number of facilities | Facility | 4 |  |
Number of employees | 3,657 |  |
Revenue from two largest customers | € | € 1,364 | € 1,220 | € 1,318
A&T [member] |  |  |
Disclosure of operating segments [line items] |  |  |
Number of facilities | Facility | 6 |  |
Number of employees | 4,008 |  |
AS&I [member] |  |  |
Disclosure of operating segments [line items] |  |  |
Number of facilities | Facility | 15 |  |
Number of employees | 3,988 |  |

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