Employees - Summary of Movements in Assets (Details) - EUR (€) € in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Disclosure of defined benefit plans [line items]
Net defined benefit liability (asset)	€ 287	€ (196)
Employee contributions	13	17
Settlements	1	7
Actual return on plan assets (excluding amounts in net finance income/charge)	1,958	1,494
Change in asset ceiling excluding amounts included in interest expenses	(17)	2
Employer contributions	394	398
Benefit payments	0	0
Other	1	(18)
Currency retranslation	127	78
Net defined benefit liability (asset)	2,993	287
Assets
Disclosure of defined benefit plans [line items]
Net defined benefit liability (asset)	24,006	23,726
Employee contributions	13	17
Settlements	0	(67)
Actual return on plan assets (excluding amounts in net finance income/charge)	1,958	1,494
Change in asset ceiling excluding amounts included in interest expenses	(17)	2
Interest income	344	436
Employer contributions	394	398
Benefit payments	(1,135)	(1,140)
Other	(47)	20
Currency retranslation	1,127	(880)
Net defined benefit liability (asset)	26,643	24,006
UK
Disclosure of defined benefit plans [line items]
Net defined benefit liability (asset)	1,351	1,121
Employee contributions	0	0
Settlements	0	0
Actual return on plan assets (excluding amounts in net finance income/charge)	1,092	1,109
Change in asset ceiling excluding amounts included in interest expenses	0	0
Employer contributions	100	104
Benefit payments	0	0
Other	0	2
Currency retranslation	126	(36)
Net defined benefit liability (asset)	2,879	1,351
UK \| Assets
Disclosure of defined benefit plans [line items]
Net defined benefit liability (asset)	12,499	12,122
Employee contributions	0	0
Settlements	0	0
Actual return on plan assets (excluding amounts in net finance income/charge)	1,092	1,109
Change in asset ceiling excluding amounts included in interest expenses	0	0
Interest income	181	230
Employer contributions	100	104
Benefit payments	(501)	(467)
Other	0	46
Currency retranslation	961	(645)
Net defined benefit liability (asset)	14,332	12,499
The Netherlands
Disclosure of defined benefit plans [line items]
Net defined benefit liability (asset)	527	425
Employee contributions	0	0
Settlements	0	0
Actual return on plan assets (excluding amounts in net finance income/charge)	560	206
Change in asset ceiling excluding amounts included in interest expenses	0	0
Employer contributions	72	12
Benefit payments	0	0
Other	0	(3)
Currency retranslation	0	0
Net defined benefit liability (asset)	1,162	527
The Netherlands \| Assets
Disclosure of defined benefit plans [line items]
Net defined benefit liability (asset)	5,587	5,522
Employee contributions	0	0
Settlements	0	0
Actual return on plan assets (excluding amounts in net finance income/charge)	560	206
Change in asset ceiling excluding amounts included in interest expenses	0	0
Interest income	39	60
Employer contributions	72	12
Benefit payments	(159)	(166)
Other	0	(47)
Currency retranslation	0	0
Net defined benefit liability (asset)	6,099	5,587
Rest of world
Disclosure of defined benefit plans [line items]
Net defined benefit liability (asset)	(1,591)	(1,742)
Employee contributions	13	17
Settlements	1	7
Actual return on plan assets (excluding amounts in net finance income/charge)	306	179
Change in asset ceiling excluding amounts included in interest expenses	(17)	2
Employer contributions	222	282
Benefit payments	0	0
Other	1	(17)
Currency retranslation	1	114
Net defined benefit liability (asset)	(1,048)	(1,591)
Rest of world \| Assets
Disclosure of defined benefit plans [line items]
Net defined benefit liability (asset)	5,920	6,082
Employee contributions	13	17
Settlements	0	(67)
Actual return on plan assets (excluding amounts in net finance income/charge)	306	179
Change in asset ceiling excluding amounts included in interest expenses	(17)	2
Interest income	124	146
Employer contributions	222	282
Benefit payments	(475)	(507)
Other	(47)	21
Currency retranslation	166	(235)
Net defined benefit liability (asset)	€ 6,212	€ 5,920

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]]

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-URIDate 2021-03-24

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- Definition

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

+ References

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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 the gain (loss) on changes in the effect of limiting a net defined benefit asset to the asset ceiling, excluding amounts included in interest income or expense. [Refer: Interest income (expense); Net defined benefit liability (asset); Increase (decrease) in net defined benefit liability (asset) resulting from interest expense (income)]

+ 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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
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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
-Name IAS
-Number 19
-IssueDate 2021-01-01
-Paragraph 141
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- Definition

The decrease (increase) in the net defined benefit liability (asset) resulting from payments from the plan in respect of settlements. [Refer: Decrease (increase) in net defined benefit liability (asset) resulting from gains (losses) arising from settlements; Net defined benefit liability (asset); Defined benefit plans [member]]

+ References

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- Definition

The decrease (increase) in the net defined benefit liability (asset) resulting from the return on plan assets, excluding amounts included in interest income or expense. The return on plan assets is interest, dividends and other revenue derived from the plan assets, together with realised and unrealised gains or losses on the plan assets, less any costs of managing plan assets and less any tax payable by the plan itself, other than tax included in the actuarial assumptions used to measure the present value of the defined benefit obligation. [Refer: Plan assets [member]; Net defined benefit liability (asset); Actuarial assumptions [member]; Increase (decrease) in net defined benefit liability (asset) resulting from interest expense (income)]

+ References

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