Inventories - Additional Information (Detail) - EUR (€) € in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Write-downs (reversals of write-downs) of inventories [Abstract]
Inventories write-down	€ 31	€ 17	€ 12

The amount of expense recognised related to the write-down of inventories to net realisable value. [Refer: Inventories]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 2
-IssueDate 2016-01-13
-Paragraph 36
-Subparagraph e
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=2&date=2016-03-30&anchor=para_36_e&doctype=Standard
-URIDate 2016-03-31

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2016-01-13
-Paragraph 98
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2016-03-30&anchor=para_98_a&doctype=Standard
-URIDate 2016-03-31

Name:	ifrs-full_InventoryWritedown2011
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration