CURRENCY GAINS / (LOSSES) - Foreign Currency Translation Reserve (Details) - EUR (€) € in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Movement in foreign currency translation reserve [abstract]
Foreign currency translation reserve at January 1	€ 3	€ (7)
Effect of currency translation differences	1	10
Foreign currency translation reserve at December 31	€ 4	€ 3

A component of equity representing exchange differences on translation of financial statements of foreign operations recognised in other comprehensive income and accumulated in equity. [Refer: Other comprehensive income]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 21
-IssueDate 2019-01-01
-Paragraph 52
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=21&code=ifrs-tx-2019-en-r&anchor=para_52_b&doctype=Standard
-URIDate 2019-03-27

Name:	ifrs-full_ReserveOfExchangeDifferencesOnTranslation
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant