Employees - Summary of Movements in Liabilities (Details) - EUR (€) € in Millions	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Disclosure of defined benefit plans [line items]
Net defined benefit liability (asset)	€ 2,993	€ 287
Gross service cost	(186)	(228)
Special termination benefits	11	15	€ 37
Past service costs including losses/(gains) on curtailments	0	18
Actuarial gains/(losses) arising from changes in demographic assumptions	(24)	(4)
Actuarial gains/(losses) arising from changes in financial assumptions	6,914	342
Actuarial gain/(loss) arising from experience adjustments	(760)	126
Benefit payments	0	0
Other	13	1
Currency retranslation	(63)	127
Net defined benefit liability (asset)	2,569	2,993	287
Present value of defined benefit obligation
Disclosure of defined benefit plans [line items]
Net defined benefit liability (asset)	(23,650)	(23,719)
Gross service cost	(186)	(228)
Special termination benefits	(11)	(15)
Past service costs including losses/(gains) on curtailments	0	18
Settlements	1	1
Interest income	(452)	(354)
Actuarial gains/(losses) arising from changes in demographic assumptions	(24)	(4)
Actuarial gains/(losses) arising from changes in financial assumptions	6,914	342
Actuarial gain/(loss) arising from experience adjustments	(760)	126
Benefit payments	1,184	1,135
Other	15	48
Currency retranslation	405	(1,000)
Net defined benefit liability (asset)	(16,564)	(23,650)	(23,719)
UK
Disclosure of defined benefit plans [line items]
Net defined benefit liability (asset)	2,879	1,351
Gross service cost	(86)	(127)
Special termination benefits	0	0
Past service costs including losses/(gains) on curtailments	0	(1)
Actuarial gains/(losses) arising from changes in demographic assumptions	1	(2)
Actuarial gains/(losses) arising from changes in financial assumptions	4,196	225
Actuarial gain/(loss) arising from experience adjustments	(276)	95
Benefit payments	0	0
Other	0	0
Currency retranslation	(99)	126
Net defined benefit liability (asset)	1,866	2,879	1,351
UK \| Present value of defined benefit obligation
Disclosure of defined benefit plans [line items]
Net defined benefit liability (asset)	(11,453)	(11,148)
Gross service cost	(86)	(127)
Special termination benefits	0	0
Past service costs including losses/(gains) on curtailments	0	(1)
Settlements	0	0
Interest income	(210)	(161)
Actuarial gains/(losses) arising from changes in demographic assumptions	1	(2)
Actuarial gains/(losses) arising from changes in financial assumptions	4,196	225
Actuarial gain/(loss) arising from experience adjustments	(276)	95
Benefit payments	511	501
Other	0	0
Currency retranslation	479	(835)
Net defined benefit liability (asset)	(6,838)	(11,453)	(11,148)
The Netherlands
Disclosure of defined benefit plans [line items]
Net defined benefit liability (asset)	1,162	527
Gross service cost	(4)	(4)
Special termination benefits	0	0
Past service costs including losses/(gains) on curtailments	0	0
Actuarial gains/(losses) arising from changes in demographic assumptions	(50)	(6)
Actuarial gains/(losses) arising from changes in financial assumptions	1,527	(23)
Actuarial gain/(loss) arising from experience adjustments	(377)	32
Benefit payments	0	0
Other	(1)	0
Currency retranslation	0	0
Net defined benefit liability (asset)	1,609	1,162	527
The Netherlands \| Present value of defined benefit obligation
Disclosure of defined benefit plans [line items]
Net defined benefit liability (asset)	(4,937)	(5,060)
Gross service cost	(4)	(4)
Special termination benefits	0	0
Past service costs including losses/(gains) on curtailments	0	0
Settlements	0	0
Interest income	(54)	(35)
Actuarial gains/(losses) arising from changes in demographic assumptions	(50)	(6)
Actuarial gains/(losses) arising from changes in financial assumptions	1,527	(23)
Actuarial gain/(loss) arising from experience adjustments	(377)	32
Benefit payments	161	159
Other	0	0
Currency retranslation	0	0
Net defined benefit liability (asset)	(3,734)	(4,937)	(5,060)
Rest of world
Disclosure of defined benefit plans [line items]
Net defined benefit liability (asset)	(1,048)	(1,591)
Gross service cost	(96)	(97)
Special termination benefits	11	15
Past service costs including losses/(gains) on curtailments	0	19
Actuarial gains/(losses) arising from changes in demographic assumptions	25	4
Actuarial gains/(losses) arising from changes in financial assumptions	1,191	140
Actuarial gain/(loss) arising from experience adjustments	(107)	(1)
Benefit payments	0	0
Other	14	1
Currency retranslation	36	1
Net defined benefit liability (asset)	(906)	(1,048)	(1,591)
Rest of world \| Present value of defined benefit obligation
Disclosure of defined benefit plans [line items]
Net defined benefit liability (asset)	(7,260)	(7,511)
Gross service cost	(96)	(97)
Special termination benefits	(11)	(15)
Past service costs including losses/(gains) on curtailments	0	19
Settlements	1	1
Interest income	(188)	(158)
Actuarial gains/(losses) arising from changes in demographic assumptions	25	4
Actuarial gains/(losses) arising from changes in financial assumptions	1,191	140
Actuarial gain/(loss) arising from experience adjustments	(107)	(1)
Benefit payments	512	475
Other	15	48
Currency retranslation	(74)	(165)
Net defined benefit liability (asset)	€ (5,992)	€ (7,260)	€ (7,511)

The decrease (increase) in a net defined benefit liability (asset) resulting from actuarial gains (losses) arising from changes in demographic assumptions that result in remeasurements of the net defined benefit liability (asset). Demographic assumptions deal with matters such as: (a) mortality; (b) rates of employee turnover, disability and early retirement; (c) the proportion of plan members with dependants who will be eligible for benefits; (d) the proportion of plan members who will select each form of payment option available under the plan terms; and (e) claim rates under medical plans. [Refer: Net defined benefit liability (asset)]

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- Definition

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

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The decrease (increase) in a net defined benefit liability (asset) resulting from actuarial gains (losses) arising from experience adjustments that result in remeasurements of the net defined benefit liability (asset). Experience adjustments deal with the effects of differences between the previous actuarial assumptions and what has actually occurred. [Refer: Net defined benefit liability (asset)]

+ References

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

The increase (decrease) in the net defined benefit liability (asset) resulting from employee service in the current period. [Refer: Net defined benefit liability (asset)]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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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 decrease (increase) in the net defined benefit liability (asset) resulting from settlements. Settlements are transactions that eliminate all further legal or constructive obligations for part or all of the benefits provided under a defined benefit plan, other than a payment of benefits to, or on behalf of, employees that is set out in the terms of the plan and included in the actuarial assumptions. [Refer: Net defined benefit liability (asset); Defined benefit plans [member]; Actuarial assumptions [member]]

+ 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
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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

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The increase (decrease) in the net defined benefit liability (asset) 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: Net defined benefit liability (asset); Defined benefit plans [member]]

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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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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

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