Trade and Other Payables Amounts Falling Due After More than One Year - Summary of Deferred and Earnout Related Obligations (Detail) - GBP (£) £ in Millions	6 Months Ended	12 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Disclosure Of Fair Value Of Contingent Consideration [abstract]
At the beginning of the period	£ 253.8	£ 414.7	£ 414.7
Earnouts paid	(88.5)	(57.9)	(130.0)
New acquisitions	2.9	3.9	9.6
Revision of estimates taken to goodwill	(3.0)	1.1	(14.3)
Revaluation of payments due to vendors (note 6)	(4.3)	8.4	1.1
Transfer to disposal group classified as held for sale			(11.5)
Exchange adjustments	5.7	1.3	(15.8)
At the end of the period	£ 166.6	£ 371.5	£ 253.8

Contingent consideration current and non-current payable to vendors (earnout agreements).

No definition available.

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Disclosure Of Fair Value Of Contingent Consideration [abstract].

No definition available.

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Earnouts paid.

No definition available.

Increase (decrease) through business combinations, contingent consideration.

No definition available.

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Namespace Prefix:	wpp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Increase (decrease) through net exchange differences, contingent consideration.

No definition available.

Name:	wpp_IncreaseDecreaseThroughNetExchangeDifferencesContingentConsideration
Namespace Prefix:	wpp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Revaluation of payments due to vendors, Increase decrease in payables

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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Revision of estimates taken to goodwill.

No definition available.

Name:	wpp_RevisionOfEstimatesTakenToGoodwill
Namespace Prefix:	wpp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Transfer to disposal group classified as held for sale from trade and other payables.

No definition available.

Name:	wpp_TransferToDisposalGroupClassifiedAsHeldForSaleFromTradeAndOtherPayables
Namespace Prefix:	wpp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration