Provisions - Movements in the Fair Value of Plan Assets (Details) - Post-employment defined benefit plans - EUR (€) € in Millions	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022
Net Defined Benefit Liability Asset [Roll Forward]
Net defined benefit asset (liability) at beginning of period	€ (309)
Net defined benefit asset (liability) at end of period	(395)	€ (309)
Fair value of plan assets
Net Defined Benefit Liability Asset [Roll Forward]
Net defined benefit asset (liability) at beginning of period	870	774
Translation differences	31	90
Interest income	77	66
Actuarial losses and gains	(30)	(3)
Company contributions	2	2
Benefits paid	(48)	(45)
Transfers	(4)	5
Other movements	(4)	(19)
Net defined benefit asset (liability) at end of period	894	870
Germany \| Operating segments
Net Defined Benefit Liability Asset [Roll Forward]
Net defined benefit asset (liability) at beginning of period	(107)
Net defined benefit asset (liability) at end of period	(133)	(107)
Germany \| Operating segments \| Fair value of plan assets
Net Defined Benefit Liability Asset [Roll Forward]
Net defined benefit asset (liability) at beginning of period	101	99
Translation differences	0	0
Interest income	3	1
Actuarial losses and gains	0	(1)
Company contributions	2	2
Benefits paid	(3)	(3)
Transfers	0	3
Other movements	0	0
Net defined benefit asset (liability) at end of period	103	101
Brazil \| Operating segments
Net Defined Benefit Liability Asset [Roll Forward]
Net defined benefit asset (liability) at beginning of period	(137)
Net defined benefit asset (liability) at end of period	(187)	(137)
Brazil \| Operating segments \| Fair value of plan assets
Net Defined Benefit Liability Asset [Roll Forward]
Net defined benefit asset (liability) at beginning of period	751	660
Translation differences	31	89
Interest income	74	65
Actuarial losses and gains	(30)	(2)
Company contributions	0	0
Benefits paid	(45)	(42)
Transfers	0	0
Other movements	(4)	(19)
Net defined benefit asset (liability) at end of period	777	751
Others \| Operating segments
Net Defined Benefit Liability Asset [Roll Forward]
Net defined benefit asset (liability) at beginning of period	(1)
Net defined benefit asset (liability) at end of period	(1)	(1)
Others \| Operating segments \| Fair value of plan assets
Net Defined Benefit Liability Asset [Roll Forward]
Net defined benefit asset (liability) at beginning of period	18	15
Translation differences	0	1
Interest income	0	0
Actuarial losses and gains	0	0
Company contributions	0	0
Benefits paid	0	0
Transfers	(4)	2
Other movements	0	0
Net defined benefit asset (liability) at end of period	€ 14	€ 18

The decrease (increase) in net defined benefit liability (asset) resulting from contributions to a defined benefit plan by the employer. [Refer: Net defined benefit liability (asset); Defined benefit plans [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 19
-IssueDate 2023-01-01
-Paragraph 141
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- Definition

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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- Definition

The increase (decrease) in the net defined benefit liability (asset) resulting from changes in foreign exchange rates. [Refer: Net defined benefit liability (asset)]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition

The increase (decrease) in the net defined benefit liability (asset) resulting from changes that the entity does not separately disclose in the same statement or note. [Refer: Net defined benefit liability (asset)]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
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-Paragraph 141
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- Definition

The increase (decrease) in the net defined benefit liability (asset) resulting from the passage of time. [Refer: Interest expense; Net defined benefit liability (asset)]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
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- Definition

The amount of deficit or surplus in a defined benefit plan, adjusted for any effect of limiting a net defined benefit asset to the asset ceiling. [Refer: Defined benefit plans [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-IssueDate 2023-01-01
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- Definition

The decrease (increase) in the net defined benefit liability (asset) resulting from payments from the plan. [Refer: Net defined benefit liability (asset)]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition

Increase (decrease) through transfers, net defined benefit liability (asset)

+ References

No definition available.

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- Definition

Net Defined Benefit Liability Asset [Roll Forward]

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