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, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure Of Fair Value Of Contingent Consideration [abstract]
At the beginning of the year	£ 630.7	£ 976.5
Earnouts paid (note 11)	(120.2)	(199.1)	£ (92.3)
New acquisitions	48.6	163.7
Revision of estimates taken to goodwill (note 12)	(68.3)	(60.7)
Revaluation of payments due to vendors (note 6)	(82.6)	(208.6)
Exchange adjustments	6.5	(41.1)
At end of year	£ 414.7	£ 630.7	£ 976.5

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

No definition available.

Name:	wpp_ContingentConsiderationCurrentAndNoncurrentPayableToVendors
Namespace Prefix:	wpp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Disclosure Of Fair Value Of Contingent Consideration [abstract].

No definition available.

Name:	wpp_DisclosureOfFairValueOfContingentConsiderationAbstract
Namespace Prefix:	wpp_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Earnouts paid.

No definition available.

Increase (decrease) through business combinations, contingent consideration.

No definition available.

Name:	wpp_IncreaseDecreaseThroughBusinessCombinationsContingentConsideration
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.

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

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