Employees - Summary of Assumptions for Pension Plans (Details)	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
United Kingdom
Disclosure of defined benefit plans [line items]
Discount rate (in percent)	1.90%	1.40%
Inflation (in percent)	3.20%	2.70%
Rate of increase in salaries (in percent)	3.70%	3.30%
Number of years a current pensioner is expected to live beyond age 65 - Men (in years)	21.8	21.7
Number of years a current pensioner is expected to live beyond age 65 - Women (in years)	23.6	23.4
Number of years a future pensioner currently aged 45 is expected to live beyond age 65 - Men (in years)	22.8	22.7
Number of years a future pensioner currently aged 45 is expected to live beyond age 65 - Women (in years)	24.8	24.6
United Kingdom \| Pensions in payment
Disclosure of defined benefit plans [line items]
Rate of increase for pensions in payment (where provided) (in percent)	3.10%	2.70%
United Kingdom \| Pensions in deferment
Disclosure of defined benefit plans [line items]
Rate of increase for pensions in deferment (where provided) (in percent)	3.10%	2.70%
The Netherlands
Disclosure of defined benefit plans [line items]
Discount rate (in percent)	1.10%	0.70%
Inflation (in percent)	1.90%	1.50%
Rate of increase in salaries (in percent)	2.40%	2.00%
Number of years a current pensioner is expected to live beyond age 65 - Men (in years)	21.6	21.5
Number of years a current pensioner is expected to live beyond age 65 - Women (in years)	23.7	23.6
Number of years a future pensioner currently aged 45 is expected to live beyond age 65 - Men (in years)	23.5	23.4
Number of years a future pensioner currently aged 45 is expected to live beyond age 65 - Women (in years)	25.5	25.4
The Netherlands \| Pensions in payment
Disclosure of defined benefit plans [line items]
Rate of increase for pensions in payment (where provided) (in percent)	1.90%	1.50%
The Netherlands \| Pensions in deferment
Disclosure of defined benefit plans [line items]
Rate of increase for pensions in deferment (where provided) (in percent)	1.90%	1.50%

The discount rate used as the significant actuarial assumption to determine the present value of a defined benefit obligation. [Refer: Defined benefit obligation, at present value; Actuarial assumptions [member]]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 19
-IssueDate 2021-01-01
-Paragraph 144
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-URIDate 2021-03-24

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The expected rate of inflation that is used as a significant actuarial assumption to determine the present value of a defined benefit obligation. [Refer: Defined benefit plans [member]; Defined benefit obligation, at present value; Actuarial assumptions [member]]

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The expected rate of salary increases used as a significant actuarial assumption to determine the present value of a defined benefit obligation. [Refer: Defined benefit plans [member]; Defined benefit obligation, at present value; Actuarial assumptions [member]]

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

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Actuarial assumption of increase for pensions in deferment where provided

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Actuarial assumption of increase for pensions in payment where provided.

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Longevity for current pensioners, females.

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Longevity for current pensioners, males.

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Longevity for future pensioners, females.

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Longevity for future pensioners, males.

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