Authorised and issued share capital - Options Granted, WPP Share Option Plan 2015 (Detail)	12 Months Ended
Dec. 31, 2019 shares ADRs £ / shares $ / ADRs	Dec. 31, 2018 shares
Ordinary shares [member]
Disclosure of range of exercise prices of outstanding share options [line items]
Number of ordinary shares under option	25,105,815	24,218,615
WPP Share Option Plan 2015 [member] \| Ordinary shares [member]
Disclosure of range of exercise prices of outstanding share options [line items]
Number of ordinary shares under option	20,397,150	18,691,100
WPP Share Option Plan 2015 [member] \| American depository receipts [member]
Disclosure of range of exercise prices of outstanding share options [line items]
Number of ordinary shares under option \| ADRs	1,396,745
WPP Share Option Plan 2015 [member] \| Exercise price group 1 [member] \| Ordinary shares [member]
Disclosure of range of exercise prices of outstanding share options [line items]
Number of ordinary shares under option	18,250
Exercise price per share \| £ / shares	£ 8.372
Exercise dates	2021 - 2025
WPP Share Option Plan 2015 [member] \| Exercise price group 1 [member] \| American depository receipts [member]
Disclosure of range of exercise prices of outstanding share options [line items]
Number of ordinary shares under option \| ADRs	347,660
Exercise dates	2021 - 2028
Exercise price per ADR \| $ / ADRs	53.140
WPP Share Option Plan 2015 [member] \| Exercise price group 2 [member] \| Ordinary shares [member]
Disclosure of range of exercise prices of outstanding share options [line items]
Number of ordinary shares under option	3,406,900
Exercise price per share \| £ / shares	£ 8.372
Exercise dates	2021 - 2028
WPP Share Option Plan 2015 [member] \| Exercise price group 2 [member] \| American depository receipts [member]
Disclosure of range of exercise prices of outstanding share options [line items]
Number of ordinary shares under option \| ADRs	347,105
Exercise dates	2022 - 2029
Exercise price per ADR \| $ / ADRs	62.590
WPP Share Option Plan 2015 [member] \| Exercise price group 3 [member] \| Ordinary shares [member]
Disclosure of range of exercise prices of outstanding share options [line items]
Number of ordinary shares under option	15,500
Exercise price per share \| £ / shares	£ 9.600
Exercise dates	2022 - 2026
WPP Share Option Plan 2015 [member] \| Exercise price group 3 [member] \| American depository receipts [member]
Disclosure of range of exercise prices of outstanding share options [line items]
Number of ordinary shares under option \| ADRs	276,790
Exercise dates	2020 - 2027
Exercise price per ADR \| $ / ADRs	88.260
WPP Share Option Plan 2015 [member] \| Exercise price group 4 [member] \| Ordinary shares [member]
Disclosure of range of exercise prices of outstanding share options [line items]
Number of ordinary shares under option	2,863,975
Exercise price per share \| £ / shares	£ 9.600
Exercise dates	2022 - 2029
WPP Share Option Plan 2015 [member] \| Exercise price group 4 [member] \| American depository receipts [member]
Disclosure of range of exercise prices of outstanding share options [line items]
Number of ordinary shares under option \| ADRs	236,265
Exercise dates	2020 - 2026
Exercise price per ADR \| $ / ADRs	105.490
WPP Share Option Plan 2015 [member] \| Exercise price group 5 [member] \| Ordinary shares [member]
Disclosure of range of exercise prices of outstanding share options [line items]
Number of ordinary shares under option	19,250
Exercise price per share \| £ / shares	£ 13.085
Exercise dates	2020 - 2024
WPP Share Option Plan 2015 [member] \| Exercise price group 5 [member] \| American depository receipts [member]
Disclosure of range of exercise prices of outstanding share options [line items]
Number of ordinary shares under option \| ADRs	188,925
Exercise dates	2018 - 2025
Exercise price per ADR \| $ / ADRs	115.940
WPP Share Option Plan 2015 [member] \| Exercise price group 6 [member] \| Ordinary shares [member]
Disclosure of range of exercise prices of outstanding share options [line items]
Number of ordinary shares under option	2,785,100
Exercise price per share \| £ / shares	£ 13.085
Exercise dates	2020 - 2027
WPP Share Option Plan 2015 [member] \| Exercise price group 7 [member] \| Ordinary shares [member]
Disclosure of range of exercise prices of outstanding share options [line items]
Number of ordinary shares under option	55,500
Exercise price per share \| £ / shares	£ 15.150
Exercise dates	2018 - 2022
WPP Share Option Plan 2015 [member] \| Exercise price group 8 [member] \| Ordinary shares [member]
Disclosure of range of exercise prices of outstanding share options [line items]
Number of ordinary shares under option	1,952,200
Exercise price per share \| £ / shares	£ 15.150
Exercise dates	2018 - 2025
WPP Share Option Plan 2015 [member] \| Exercise price group 9 [member] \| Ordinary shares [member]
Disclosure of range of exercise prices of outstanding share options [line items]
Number of ordinary shares under option	5,375
Exercise price per share \| £ / shares	£ 15.150
Exercise dates	2019 - 2025
WPP Share Option Plan 2015 [member] \| Exercise price group 10 [member] \| Ordinary shares [member]
Disclosure of range of exercise prices of outstanding share options [line items]
Number of ordinary shares under option	12,375
Exercise price per share \| £ / shares	£ 17.055
Exercise dates	2019 - 2023
WPP Share Option Plan 2015 [member] \| Exercise price group 11 [member] \| Ordinary shares [member]
Disclosure of range of exercise prices of outstanding share options [line items]
Number of ordinary shares under option	2,279,000
Exercise price per share \| £ / shares	£ 17.055
Exercise dates	2019 - 2026