Statement Of Cash Flows [Abstract]
| Concept |
As at 2022-12-31 |
2022-01-01 to 2022-12-31 |
As at 2021-12-31 |
2021-01-01 to 2021-12-31 |
As at 2020-12-31 |
|---|---|---|---|---|---|
| Statement of cash flows [abstract] | |||||
| Cash flows from (used in) operating activities [abstract] | |||||
| Cash flows from (used in) operations | — |
556,300,000
GBP
|
— |
371,300,000
GBP
|
— |
| Interest received, classified as operating activities | — |
58,700,000
GBP
|
— |
46,600,000
GBP
|
— |
| Income taxes paid (refund), classified as operating activities | — |
91,200,000
GBP
|
— |
126,700,000
GBP
|
— |
| Cash flows from (used in) operating activities | — |
465,100,000
GBP
|
— |
244,600,000
GBP
|
— |
| Cash flows from (used in) investing activities [abstract] | |||||
| Purchase of property, plant and equipment, classified as investing activities | — |
98,600,000
GBP
|
— |
69,200,000
GBP
|
— |
| Cash flows from (used in) investing activities | — |
101,000,000
GBP
|
— |
387,800,000
GBP
|
— |
| Cash flows from (used in) financing activities [abstract] | |||||
| Payments of lease liabilities, classified as financing activities | — |
9,200,000
GBP
|
— |
9,600,000
GBP
|
— |
| Dividends paid, classified as financing activities | — |
658,300,000
GBP
|
— |
720,900,000
GBP
|
— |
| Interest paid, classified as financing activities | — |
25,300,000
GBP
|
— |
20,200,000
GBP
|
— |
| Cash flows from (used in) financing activities | — |
425,000,000
GBP
|
— |
564,800,000
GBP
|
— |
| Increase (decrease) in cash and cash equivalents before effect of exchange rate changes | — |
60,900,000
GBP
|
— |
67,600,000
GBP
|
— |
| Effect of exchange rate changes on cash and cash equivalents [abstract] | |||||
| Effect of exchange rate changes on cash and cash equivalents | — |
14,800,000
GBP
|
— |
5,300,000
GBP
|
— |
| Cash and cash equivalents |
297,000,000
GBP
|
— |
372,700,000
GBP
|
— |
351,700,000
GBP
|