Employees - Summary of Charge to Operating Profit (Details) - EUR (€) € in Millions	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Disclosure of defined benefit plans [line items]
Gross service cost	€ (178)	€ (128)	€ (186)
Employee contributions	37	11	12
Special termination benefits	(5)	(14)	(11)
Past service cost including (losses)/gains on curtailments	32	3	0
Settlements	5	2	1
Defined contribution plans	(230)	(222)	(212)
Post-employment benefit expense in profit or loss	(268)	(238)	(352)
United Kingdom
Disclosure of defined benefit plans [line items]
Special termination benefits	0	0
Past service cost including (losses)/gains on curtailments	28
Operating cost
Disclosure of defined benefit plans [line items]
Post-employment benefit expense in profit or loss	(339)	(348)	(396)
Finance income/(cost)
Disclosure of defined benefit plans [line items]
Post-employment benefit expense in profit or loss	€ 71	€ 110	€ 44

The expense of employee service in the current period arising from defined benefit plans. [Refer: Post-employment benefit expense in profit or loss, defined benefit plans] [Contrast: Increase in net defined benefit liability (asset) resulting from current service cost]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 19
-IssueDate 2024-01-01
-Paragraph 135
-Subparagraph b
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-URIDate 2024-03-27

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- Definition

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with members defined in one or many axes of the table.

+ References

No definition available.

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The amount of employee contributions to retirement benefit plans.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 26
-IssueDate 2024-01-01
-Paragraph 35
-Subparagraph b
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- Definition

The amount of expense (income) resulting from past service cost and losses (gains) arising from settlements. [Refer: Post-employment benefit expense in profit or loss, defined benefit plans; Past service cost, defined benefit plans] [Contrast: Increase (decrease) in net defined benefit liability (asset) resulting from past service cost and losses (gains) arising from settlements]

+ References

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The amount of expense (income) resulting from past service cost. Past service cost is the change in the present value of the defined benefit obligation for employee service in prior periods, resulting from a plan amendment (the introduction or withdrawal of, or changes to, a defined benefit plan) or a curtailment (a significant reduction by the entity in the number of employees covered by a plan). [Refer: Post-employment benefit expense in profit or loss, defined benefit plans; Defined benefit plans [domain]] [Contrast: Increase (decrease) in net defined benefit liability (asset) resulting from past service cost]

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- Definition

The amount of post-employment benefit expense relating to defined contribution plans. Defined contribution plans are post-employment benefit plans under which an entity pays fixed contributions into a separate entity (a fund) and will have no legal or constructive obligation to pay further contributions if the fund does not hold sufficient assets to pay all employee benefits relating to employee service in the current and prior periods.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 19
-IssueDate 2024-01-01
-Paragraph 53
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2024-en-r&anchor=para_53&doctype=Standard
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- Definition

The amount of post-employment benefit expense included in profit or loss

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 19
-IssueDate 2024-01-01
-Paragraph 5
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- Definition

The amount of expense in relation to termination benefits. Termination benefits are employee benefits provided in exchange for the termination of an employee's employment as a result of either: (a) an entity's decision to terminate an employee's employment before the normal retirement date; or (b) an employee's decision to accept an offer of benefits in exchange for the termination of employment. [Refer: Employee benefits expense]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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