Revenue recognition - Contract assets and liabilities (Details) - EUR (€) € in Millions	12 Months Ended
Dec. 31, 2018	Jan. 01, 2018
Revenue recognition
Contract assets	€ 1,875	€ 1,919
Contract liabilities	3,496	3,694
Non-current contract liabilities	1,113	1,216
Current contract liabilities	2,383	€ 2,478
Satisfied performance obligations	€ 1,700

The amount of an entity’s right to consideration in exchange for goods or services that the entity has transferred to a customer, when that right is conditioned on something other than the passage of time (for example, the entity’s future performance).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 15
-IssueDate 2018-01-01
-Paragraph 105
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=15&date=2018-03-01&anchor=para_105&doctype=Standard
-URIDate 2018-03-16

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 15
-IssueDate 2018-01-01
-Paragraph 116
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=15&date=2018-03-01&anchor=para_116_a&doctype=Standard
-URIDate 2018-03-16

+ Details

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

- Definition

The amount of an entity’s obligation to transfer goods or services to a customer for which the entity has received consideration (or the amount is due) from the customer.

+ References

+ Details

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

- Definition

The amount of current contract liabilities. [Refer: Contract liabilities]

+ References

+ Details

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

- Definition

The decrease in contract liabilities resulting from the performance obligation being satisfied. [Refer: Contract liabilities; Performance obligations [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name IFRS
-Number 15
-IssueDate 2018-01-01
-Paragraph 118
-Subparagraph e
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=15&date=2018-03-01&anchor=para_118_e&doctype=Standard
-URIDate 2018-03-16

+ Details

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

Name:	ifrs-full_DisclosureOfDisaggregationOfRevenueFromContractsWithCustomersAbstract
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of non-current contract liabilities. [Refer: Contract liabilities]

+ References

+ Details

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