Revenues and other income - Associated with liabilities and performance obligations (Details) - EUR (€) € in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Revenues and other income
Revenues associated with contract liabilities at the beginning of the period	€ 747	€ 342
Revenues associated with performance obligations totally or partially satisfied in previous years	€ 10	€ 11

The amount of revenue from performance obligations satisfied (or partially satisfied) in previous periods. [Refer: Performance obligations [member]; Revenue from contracts with customers]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 15
-IssueDate 2019-01-01
-Paragraph 116
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=15&code=ifrs-tx-2019-en-r&anchor=para_116_c&doctype=Standard
-URIDate 2019-03-27

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