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Pensions and Other Post-Employment Benefit Obligations - Summary of Amounts recognized in the Unaudited Interim Consolidated Income Statement (Detail) - Consolidated Income Statement [member] - EUR (€) € in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement [LineItems]
Current service cost	€ (6)	€ (5)	€ (12)	€ (11)
Net interest	(4)	(4)	(8)	(8)
Immediate recognition of gains / (losses) arising over the period	(2)		(2)
Administrative expenses		(1)	(1)	(1)
Total	(12)	(10)	(23)	(20)
Pension Benefits [member]
Statement [LineItems]
Current service cost	(5)	(3)	(9)	(8)
Net interest	(2)	(2)	(4)	(4)
Administrative expenses		(1)	(1)	(1)
Total	(7)	(6)	(14)	(13)
Other benefits [member]
Statement [LineItems]
Current service cost	(1)	(2)	(3)	(3)
Net interest	(2)	(2)	(4)	(4)
Immediate recognition of gains / (losses) arising over the period	(2)		(2)
Total	€ (5)	€ (4)	€ (9)	€ (7)

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- Definition

Defined benefit plan net periodic benefit cost.

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- Definition

The amount of expenses that the entity classifies as being administrative.

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- Definition

The increase (decrease) in the net defined benefit liability (asset) resulting from employee service in the current period. [Refer: Net defined benefit liability (asset)]

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