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Operating Segment Information - Summary of Segment Capital Expenditures (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 capital expenditures [line items] |  |  |  |
Segment capital expenditures | € (50) | € (60) | € (97) | € (120)
P&ARP [member] |  |  |  |
Disclosure of segment capital expenditures [line items] |  |  |  |
Segment capital expenditures | (17) | (24) | (30) | (48)
A&T [member] |  |  |  |
Disclosure of segment capital expenditures [line items] |  |  |  |
Segment capital expenditures | (10) | (18) | (23) | (34)
AS&I [member] |  |  |  |
Disclosure of segment capital expenditures [line items] |  |  |  |
Segment capital expenditures | (22) | (17) | (42) | (36)
Holdings & Corporate [member] |  |  |  |
Disclosure of segment capital expenditures [line items] |  |  |  |
Segment capital expenditures | € (1) | € (1) | € (2) | € (2)

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