Other Income - Summary of Other Income (Detail) - EUR (€) € in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of Other Operating Income [abstract]
Other income	€ 8	€ 540	€ 66

The amount of operating income that the entity does not separately disclose in the same statement or note.

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