Trade and Other Payables Amounts Falling Due After More than One Year - Summary of Contingent Consideration (Detail) - GBP (£) £ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Disclosure Of Fair Value Of Contingent Consideration [abstract]
At the beginning of the year	£ 414.7	£ 630.7
Earnouts paid	(130.0)	(120.2)
New acquisitions	9.6	48.6
Revision of estimates taken to goodwill (note 14)	(14.3)	(68.3)
Revaluation of payments due to vendors	1.1	(82.6)
Transfer to disposal group classified as held for sale	(11.5)	0.0
Exchange adjustments	(15.8)	6.5
At end of year	£ 253.8	£ 414.7

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

No definition available.

Name:	wpp_IncreaseDecreaseThroughNetExchangeDifferencesContingentConsideration
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Data Type:	xbrli:monetaryItemType
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Revaluation of payments due to vendors, Increase decrease in payables

No definition available.

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

No definition available.

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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.

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Data Type:	xbrli:monetaryItemType
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