Equity - Items not reclassified: benefits (Details) - EUR (€) € in Millions	6 Months Ended
Jun. 30, 2018	Dec. 31, 2017
Disclosure of analysis of other comprehensive income by item [line items]
Decrease in benefit liability from remeasurement	€ 981
Actuarial assumption of expected rates of inflation	3.07%
Spain
Disclosure of analysis of other comprehensive income by item [line items]
Decrease (increase) in accumulated actuarial losses/profits	€ 126
Actuarial assumption of discount rates	1.75%	1.40%
United Kingdom
Disclosure of analysis of other comprehensive income by item [line items]
Decrease (increase) in accumulated actuarial losses/profits	€ 603
Actuarial assumption of discount rates	2.74%	2.49%
Actuarial assumption of expected rates of inflation	3.07%
Brazil
Disclosure of analysis of other comprehensive income by item [line items]
Decrease (increase) in accumulated actuarial losses/profits	€ 155
Brazil \| Pension benefits
Disclosure of analysis of other comprehensive income by item [line items]
Actuarial assumption of discount rates	10.12%	9.53%
Brazil \| Medical benefits
Disclosure of analysis of other comprehensive income by item [line items]
Actuarial assumption of discount rates	10.17%	9.65%
Other Regions [Member] \| Discount rate actuarial assumptions
Disclosure of analysis of other comprehensive income by item [line items]
Decrease (increase) in accumulated actuarial losses/profits	€ 97
United Kingdom and Brazil
Disclosure of analysis of other comprehensive income by item [line items]
Actuarial assumption of discount rates	2.74%	2.49%
Actuarial assumption of expected rates of inflation		3.15%

The discount rate used as the significant actuarial assumption to determine the present value of a defined benefit obligation. [Refer: Defined benefit obligation, at present value; Actuarial assumptions [member]]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
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-IssueDate 2017-01-01
-Paragraph 144
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The expected rate of inflation that is used as a significant actuarial assumption to determine the present value of a defined benefit obligation. [Refer: Defined benefit plans [member]; Defined benefit obligation, at present value; Actuarial assumptions [member]]

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The decrease (increase) in a net defined benefit liability (asset) resulting from actuarial gains (losses) arising from changes in financial assumptions that result in remeasurements of the net defined benefit liability (asset). Financial assumptions deal with items such as: (a) the discount rate; (b) benefit levels, excluding any cost of the benefits to be met by employees, and future salary; (c) in the case of medical benefits, future medical costs, including claim handling costs (ie the costs that will be incurred in processing and resolving claims, including legal and adjuster's fees); and (d) taxes payable by the plan on contributions relating to service before the reporting date or on benefits resulting from that service. [Refer: Net defined benefit liability (asset)]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 19
-IssueDate 2017-01-01
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Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

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No definition available.

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The decrease (increase) in a net defined benefit liability (asset) resulting from the remeasurement of that net defined benefit liability (asset). [Refer: Net defined benefit liability (asset)]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-URIDate 2017-03-09

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