Employees - Summary of Movements in Liabilities (Details) - EUR (€) € in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disclosure of defined benefit plans [line items]
Net defined benefit liability (asset)	€ 287	€ (196)
Current service cost	(228)	(223)
Special termination benefits	15	37	€ 5
Past service costs including losses/(gains) on curtailments	18	20
Actuarial gains/(losses) arising from changes in demographic assumptions	(4)	246
Actuarial gains/(losses) arising from changes in financial assumptions	342	(1,414)
Actuarial gain/(loss) arising from experience adjustments	126	(78)
Benefit payments	0	0
Other	1	(18)
Currency retranslation	127	78
Net defined benefit liability (asset)	2,993	287	(196)
Liabilities
Disclosure of defined benefit plans [line items]
Net defined benefit liability (asset)	(23,719)	(23,922)
Current service cost	(228)	(223)
Special termination benefits	(15)	(37)
Past service costs including losses/(gains) on curtailments	18	20
Settlements	1	74
Interest income	(354)	(445)
Actuarial gains/(losses) arising from changes in demographic assumptions	(4)	246
Actuarial gains/(losses) arising from changes in financial assumptions	342	(1,414)
Actuarial gain/(loss) arising from experience adjustments	126	(78)
Benefit payments	1,135	1,140
Other	48	(38)
Currency retranslation	(1,000)	958
Net defined benefit liability (asset)	(23,650)	(23,719)	(23,922)
UK
Disclosure of defined benefit plans [line items]
Net defined benefit liability (asset)	1,351	1,121
Current service cost	(127)	(114)
Special termination benefits	0	0
Past service costs including losses/(gains) on curtailments	(1)	17
Actuarial gains/(losses) arising from changes in demographic assumptions	(2)	(1)
Actuarial gains/(losses) arising from changes in financial assumptions	225	(806)
Actuarial gain/(loss) arising from experience adjustments	95	(67)
Benefit payments	0	0
Other	0	2
Currency retranslation	126	(36)
Net defined benefit liability (asset)	2,879	1,351	1,121
UK \| Liabilities
Disclosure of defined benefit plans [line items]
Net defined benefit liability (asset)	(11,148)	(11,001)
Current service cost	(127)	(114)
Special termination benefits	0	0
Past service costs including losses/(gains) on curtailments	(1)	17
Settlements	0	0
Interest income	(161)	(208)
Actuarial gains/(losses) arising from changes in demographic assumptions	(2)	(1)
Actuarial gains/(losses) arising from changes in financial assumptions	225	(806)
Actuarial gain/(loss) arising from experience adjustments	95	(67)
Benefit payments	501	467
Other	0	(44)
Currency retranslation	(835)	609
Net defined benefit liability (asset)	(11,453)	(11,148)	(11,001)
The Netherlands
Disclosure of defined benefit plans [line items]
Net defined benefit liability (asset)	527	425
Current service cost	(4)	(3)
Special termination benefits	0	0
Past service costs including losses/(gains) on curtailments	0	0
Actuarial gains/(losses) arising from changes in demographic assumptions	(6)	245
Actuarial gains/(losses) arising from changes in financial assumptions	(23)	(354)
Actuarial gain/(loss) arising from experience adjustments	32	(6)
Benefit payments	0	0
Other	0	(3)
Currency retranslation	0	0
Net defined benefit liability (asset)	1,162	527	425
The Netherlands \| Liabilities
Disclosure of defined benefit plans [line items]
Net defined benefit liability (asset)	(5,060)	(5,097)
Current service cost	(4)	(3)
Special termination benefits	0	0
Past service costs including losses/(gains) on curtailments	0	0
Settlements	0	0
Interest income	(35)	(55)
Actuarial gains/(losses) arising from changes in demographic assumptions	(6)	245
Actuarial gains/(losses) arising from changes in financial assumptions	(23)	(354)
Actuarial gain/(loss) arising from experience adjustments	32	(6)
Benefit payments	159	166
Other	0	44
Currency retranslation	0	0
Net defined benefit liability (asset)	(4,937)	(5,060)	(5,097)
Rest of world
Disclosure of defined benefit plans [line items]
Net defined benefit liability (asset)	(1,591)	(1,742)
Current service cost	(97)	(106)
Special termination benefits	15	37
Past service costs including losses/(gains) on curtailments	19	3
Actuarial gains/(losses) arising from changes in demographic assumptions	4	2
Actuarial gains/(losses) arising from changes in financial assumptions	140	(254)
Actuarial gain/(loss) arising from experience adjustments	(1)	(5)
Benefit payments	0	0
Other	1	(17)
Currency retranslation	1	114
Net defined benefit liability (asset)	(1,048)	(1,591)	(1,742)
Rest of world \| Liabilities
Disclosure of defined benefit plans [line items]
Net defined benefit liability (asset)	(7,511)	(7,824)
Current service cost	(97)	(106)
Special termination benefits	(15)	(37)
Past service costs including losses/(gains) on curtailments	19	3
Settlements	1	74
Interest income	(158)	(182)
Actuarial gains/(losses) arising from changes in demographic assumptions	4	2
Actuarial gains/(losses) arising from changes in financial assumptions	140	(254)
Actuarial gain/(loss) arising from experience adjustments	(1)	(5)
Benefit payments	475	507
Other	48	(38)
Currency retranslation	(165)	349
Net defined benefit liability (asset)	€ (7,260)	€ (7,511)	€ (7,824)

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)]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 19
-IssueDate 2021-01-01
-Paragraph 141
-Subparagraph c
-Clause ii
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_141_c_ii&doctype=Standard
-URIDate 2021-03-24

+ Details

Name:	ifrs-full_ActuarialGainsLossesArisingFromChangesInDemographicAssumptionsNetDefinedBenefitLiabilityAsset
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 19
-IssueDate 2021-01-01
-Paragraph 141
-Subparagraph c
-Clause iii
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_141_c_iii&doctype=Standard
-URIDate 2021-03-24

+ Details

Name:	ifrs-full_ActuarialGainsLossesArisingFromChangesInFinancialAssumptionsNetDefinedBenefitLiabilityAsset
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

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
-Name IAS
-Number 19
-IssueDate 2021-01-01
-Paragraph 141
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_141_c&doctype=Standard
-URIDate 2021-03-24

+ Details

Name:	ifrs-full_ActuarialGainsLossesArisingFromExperienceAdjustmentsNetDefinedBenefitLiabilityAsset
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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
-Name IAS
-Number 19
-IssueDate 2021-01-01
-Paragraph 141
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_141_a&doctype=Standard
-URIDate 2021-03-24

+ Details

Name:	ifrs-full_CurrentServiceCostNetDefinedBenefitLiabilityAsset
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- 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.

+ Details

Name:	ifrs-full_DisclosureOfDefinedBenefitPlansLineItems
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

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
-Name IAS
-Number 19
-IssueDate 2021-01-01
-Paragraph 141
-Subparagraph d
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_141_d&doctype=Standard
-URIDate 2021-03-24

+ Details

Name:	ifrs-full_GainsLossesArisingFromSettlementsNetDefinedBenefitLiabilityAsset
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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
-Name IAS
-Number 19
-IssueDate 2021-01-01
-Paragraph 141
-Subparagraph e
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_141_e&doctype=Standard
-URIDate 2021-03-24

+ Details

Name:	ifrs-full_IncreaseDecreaseThroughChangesInForeignExchangeRatesNetDefinedBenefitLiabilityAsset
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- 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
-Number 19
-IssueDate 2021-01-01
-Paragraph 141
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_141&doctype=Standard
-URIDate 2021-03-24

+ Details

Name:	ifrs-full_IncreaseDecreaseThroughOtherChangesNetDefinedBenefitLiabilityAsset
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- 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
-Number 19
-IssueDate 2021-01-01
-Paragraph 141
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_141_b&doctype=Standard
-URIDate 2021-03-24

+ Details

Name:	ifrs-full_InterestExpenseIncomeNetDefinedBenefitLiabilityAsset
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- 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
-Number 19
-IssueDate 2021-01-01
-Paragraph 140
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_140_a&doctype=Standard
-URIDate 2021-03-24

+ Details

Name:	ifrs-full_LiabilityAssetOfDefinedBenefitPlans
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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]]

+ References

+ Details

Name:	ifrs-full_PastServiceCostNetDefinedBenefitLiabilityAsset
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- 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
-Subparagraph g
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_141_g&doctype=Standard
-URIDate 2021-03-24

+ Details

Name:	ifrs-full_PaymentsFromPlanNetDefinedBenefitLiabilityAsset
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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
-Name IAS
-Number 19
-IssueDate 2021-01-01
-Paragraph 171
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_171&doctype=Standard
-URIDate 2021-03-24

+ Details

Name:	ifrs-full_TerminationBenefitsExpense
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	ifrs-full_NetDefinedBenefitLiabilityAssetAxis=ifrs-full_PresentValueOfDefinedBenefitObligationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_GeographicalAreasAxis=country_GB
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_GeographicalAreasAxis=country_NL
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_GeographicalAreasAxis=ul_AllOtherCountriesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: