Treasury Risk Management - Summary of Derivatives Used to Hedge (Detail) - EUR (€) € in Millions	Dec. 31, 2018	Dec. 31, 2017
Disclosure of detailed information about hedges [line items]
Financial assets	€ 4,746	€ 4,762
Trade payables and other liabilities	(14,803)	(14,126)
Current financial liabilities	(3,235)	(7,968)
Non-current financial liabilities	(21,650)	(16,462)
Derivatives designated as hedges [member]
Disclosure of detailed information about hedges [line items]
Trade and other receivable	82	57
Financial assets	194	116
Trade payables and other liabilities	(140)	(113)
Current financial liabilities	(126)	(86)
Non-current financial liabilities	(276)	(335)
Total	(266)	(361)
Derivative used to hedge [Member]
Disclosure of detailed information about hedges [line items]
Total Financial assets	276	173
Financial assets	276	173
Total financial liabilities	(542)	(534)
Non-current financial liabilities	(542)	(534)
Total	(266)	(361)
Fair value hedges [member] \| Cross currency interest rate swaps contract [member] \| Derivatives designated as hedges [member]
Disclosure of detailed information about hedges [line items]
Financial assets		2
Total		2
Cash flow hedges [member] \| Foreign exchange derivatives [member] \| Derivatives designated as hedges [member]
Disclosure of detailed information about hedges [line items]
Trade and other receivable	39	32
Trade payables and other liabilities	(25)	(40)
Total	14	(8)
Cash flow hedges [member] \| Cross currency interest rate swaps contract [member] \| Derivatives designated as hedges [member]
Disclosure of detailed information about hedges [line items]
Financial assets	69	2
Current financial liabilities		(18)
Non-current financial liabilities	(268)	(335)
Total	(199)	(351)
Cash flow hedges [member] \| Commodity contracts [Member] \| Derivatives designated as hedges [member]
Disclosure of detailed information about hedges [line items]
Trade and other receivable		12
Trade payables and other liabilities	(74)	(19)
Total	(74)	(7)
Hedges of net investment in foreign operations [member] \| Foreign exchange derivatives [member] \| Derivatives designated as hedges [member]
Disclosure of detailed information about hedges [line items]
Financial assets	58	9
Current financial liabilities	(21)	(103)
Total	37	(94)
Hedge accounting not applied [member] \| Foreign exchange derivatives [member] \| Derivatives designated as hedges [member]
Disclosure of detailed information about hedges [line items]
Trade and other receivable	42	13
Financial assets	67	73
Trade payables and other liabilities	(41)	(54)
Current financial liabilities	(105)	35
Total	(37)	67
Hedge accounting not applied [member] \| Cross currency interest rate swaps contract [member] \| Derivatives designated as hedges [member]
Disclosure of detailed information about hedges [line items]
Financial assets		30
Non-current financial liabilities	(8)
Total	(8)	€ 30
Hedge accounting not applied [member] \| Commodity contracts [Member] \| Derivatives designated as hedges [member]
Disclosure of detailed information about hedges [line items]
Trade and other receivable	1
Total	€ 1

The amount of current financial liabilities. [Refer: Financial liabilities]

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

- Definition

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

+ References

No definition available.

+ Details

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

- Definition

The amount of assets that are: (a) cash; (b) an equity instrument of another entity; (c) a contractual right: (i) to receive cash or another financial asset from another entity; or (ii) to exchange financial assets or financial liabilities with another entity under conditions that are potentially favourable to the entity; or (d) a contract that will, or may be, settled in the entity’s own equity instruments and is: (i) a non-derivative for which the entity is, or may be, obliged to receive a variable number of the entity’s own equity instruments; or (ii) a derivative that will, or may be, settled other than by the exchange of a fixed amount of cash or another financial asset for a fixed number of the entity’s own equity instruments. For this purpose the entity’s own equity instruments do not include puttable financial instruments classified as equity instruments in accordance with paragraphs 16A-16B of IAS 32, instruments that impose on the entity an obligation to deliver to another party a pro rata share of the net assets of the entity only on liquidation and are classified as equity instruments in accordance with paragraphs 16C-16D of IAS 32, or instruments that are contracts for the future receipt or delivery of the entity’s own equity instruments. [Refer: Financial instruments, class [member]; Financial liabilities]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 25
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_25&doctype=Standard
-URIDate 2017-03-09

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2018-01-01
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 35H
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_35H&doctype=Standard
-URIDate 2017-03-09

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2018-01-01
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 35I
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_35I&doctype=Standard
-URIDate 2017-03-09

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2018-01-01
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 35M
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_35M&doctype=Standard
-URIDate 2017-03-09

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Note Effective 2018-01-01
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 35N
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_35N&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_FinancialAssets
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of non-current financial liabilities. [Refer: Financial liabilities]

+ References

+ Details

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

- Definition

The amount of trade payables and other payables. [Refer: Trade payables; Other payables]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 54
-Subparagraph k
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_54_k&doctype=Standard
-URIDate 2017-03-09

+ Details

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

- Definition

The amount of trade receivables and other receivables. [Refer: Trade receivables; Other receivables]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 54
-Subparagraph h
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_54_h&doctype=Standard
-URIDate 2017-03-09

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 78
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_78_b&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_TradeAndOtherReceivables
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Derivative financial assets liabilities, net.

+ References

No definition available.

+ Details

Name:	ul_DerivativeFinancialAssetsLiabilitiesNet
Namespace Prefix:	ul_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Gross financial assets in derivatives

+ References

No definition available.

+ Details

Name:	ul_GrossFinancialAssetsInDerivatives
Namespace Prefix:	ul_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Gross liabilities in derivatives.

+ References

No definition available.

+ Details

Name:	ul_GrossLiabilitiesInDerivatives
Namespace Prefix:	ul_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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

- Details

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

- Details

Name:	ifrs-full_TypesOfHedgesAxis=ifrs-full_FairValueHedgesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfFinancialAssetsAxis=ul_CrossCurrencyInterestRateSwapsContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_TypesOfHedgesAxis=ifrs-full_CashFlowHedgesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfFinancialAssetsAxis=ul_ForeignExchangeDerivativesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfFinancialAssetsAxis=ul_CommodityContractsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_TypesOfHedgesAxis=ifrs-full_HedgesOfNetInvestmentInForeignOperationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_TypesOfHedgesAxis=ul_HedgeAccountingNotAppliedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: