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Currency Gains / (Losses) - Summary of Foreign Currency Translation Reserve (Detail) - EUR (€) € in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Movement in foreign currency translation reserve [abstract]
Foreign currency translation reserve at January 1	€ 12	€ 6
Effect of currency translation differences-net	(19)	6
Foreign currency translation reserve at December 31	€ (7)	€ 12

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- Definition

Movement in foreign currency translation reserve.

+ References

No definition available.

+ Details

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- Definition

The gains (losses) recognised in other comprehensive income on exchange differences on the translation of financial statements of foreign operations, before tax. [Refer: Other comprehensive income]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 91
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_91_b&doctype=Standard
-URIDate 2017-03-09

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- Definition

A component of equity representing exchange differences on translation of financial statements of foreign operations recognised in other comprehensive income and accumulated in equity. [Refer: Other comprehensive income]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 21
-IssueDate 2017-01-01
-Paragraph 52
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=21&date=2017-03-01&anchor=para_52_b&doctype=Standard
-URIDate 2017-03-09

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