Related Party Transactions - Summary of Key Management Remuneration (Detail) - EUR (€) € in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Related party transactions [Abstract]
Short-term benefits	€ 9	€ 13	€ 10
Post-employment benefits	1	1	1
Share-based payments - calculated in accordance with the principles disclosed in note 8	3	3	2
Total	€ 13	€ 17	€ 13

The amount of compensation to key management personnel. [Refer: Key management personnel of entity or parent [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 24
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-URIDate 2016-03-31

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- Definition

The amount of compensation to key management personnel in the form of post-employment benefits. [Refer: Key management personnel of entity or parent [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 24
-IssueDate 2016-01-13
-Paragraph 17
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- Definition

The amount of compensation to key management personnel in the form of share-based payments. [Refer: Key management personnel of entity or parent [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 24
-IssueDate 2016-01-13
-Paragraph 17
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- Definition

The amount of compensation to key management personnel in the form of short-term employee benefits. [Refer: Key management personnel of entity or parent [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 24
-IssueDate 2016-01-13
-Paragraph 17
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-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=24&date=2016-03-30&anchor=para_17_a&doctype=Standard
-URIDate 2016-03-31

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- References

No definition available.

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