Business Combinations - Summary of Post Acquisition Impact (Detail) - Post acquisition impact [Member] - EUR (€) € in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about business combination [Line Items]
Revenue	€ 532	€ 101	€ 2,679
(Loss)/profit before tax for the financial year	€ (2)	€ 1	€ (7)

The amount of revenue of the acquiree since the acquisition date included in the consolidated statement of comprehensive income. [Refer: Revenue]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 3
-IssueDate 2016-01-13
-Paragraph B64
-Subparagraph q
-Clause i
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=3&date=2016-03-30&anchor=para_B64_q_i&doctype=Appendix&seq=2
-URIDate 2016-03-31

Name:	ifrs-full_RevenueOfAcquiree
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration