Defined Benefit Plans - Summary of Amounts Recognized in Statement of Financial Positions (Parenthetical) (Detail) - EUR (€) € in Millions	Dec. 31, 2018	Dec. 31, 2017
Disclosure of net defined benefit liability (asset) [abstract]
Assets held	€ 2,568	€ 2,457

The amount that securities that are backed by underlying assets constitute of the fair value of defined benefit plan assets. [Refer: Plan assets, at fair value; Defined benefit plans [member]]

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 19
-IssueDate 2018-01-01
-Paragraph 142
-Subparagraph g
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2018-03-01&anchor=para_142_g&doctype=Standard
-URIDate 2018-03-16

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