Related Party Transactions - Summary of Related Party Balances Existed with Associate or Joint Venture Businesses (Detail) - EUR (€) € in Millions	Dec. 31, 2017	Dec. 31, 2016
Joint Ventures Where Entity is Venturer [Member]
Disclosure of Transactions between Related Parties [Line Items]
Trading and other balances due from joint ventures	€ 124	€ 115
Associates [Member]
Disclosure of Transactions between Related Parties [Line Items]
Trading and other balances due from/(to) associates	€ 0	€ 0

The amounts receivable resulting from related party transactions. [Refer: Related parties [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 24
-IssueDate 2016-01-13
-Paragraph 20
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=24&date=2016-03-30&anchor=para_20&doctype=Standard
-URIDate 2016-03-31

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 24
-IssueDate 2016-01-13
-Paragraph 18
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=24&date=2016-03-30&anchor=para_18_b&doctype=Standard
-URIDate 2016-03-31

Name:	ifrs-full_AmountsReceivableRelatedPartyTransactions
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant