Statement Of Changes In Equity [Abstract]
| Concept |
As at 2022-12-31 |
2022-01-01 to 2022-12-31 |
2022-01-01 to 2022-12-31 |
2022-01-01 to 2022-12-31 |
2022-01-01 to 2022-12-31 |
As at 2022-12-31 |
As at 2022-12-31 |
As at 2022-12-31 |
As at 2022-12-31 |
2022-01-01 to 2022-12-31 |
2022-01-01 to 2022-12-31 |
2022-01-01 to 2022-12-31 |
As at 2021-12-31 |
As at 2021-12-31 |
2021-01-01 to 2021-12-31 |
As at 2021-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
As at 2021-12-31 |
2021-01-01 to 2021-12-31 |
As at 2021-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
As at 2020-12-31 |
As at 2020-12-31 |
As at 2020-12-31 |
As at 2020-12-31 |
As at 2020-12-31 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of changes in equity [abstract] | |||||||||||||||||||||||||||||
| Statement of changes in equity [line items] | |||||||||||||||||||||||||||||
| Equity |
1,220,800,000
GBP
|
— | — | — | — |
115,400,000
GBP
|
83,100,000
GBP
|
1,011,300,000
GBP
|
11,000,000
GBP
|
— | — | — |
1,147,900,000
GBP
|
88,700,000
GBP
|
— |
1,330,700,000
GBP
|
— | — | — |
83,100,000
GBP
|
— |
11,000,000
GBP
|
— | — |
1,059,200,000
GBP
|
11,000,000
GBP
|
117,300,000
GBP
|
83,100,000
GBP
|
1,270,600,000
GBP
|
| Changes in equity [abstract] | |||||||||||||||||||||||||||||
| Comprehensive income [abstract] | |||||||||||||||||||||||||||||
| Profit (loss) | — | — | — |
81,900,000
GBP
|
— | — | — | — | — | — |
–
GBP
|
81,900,000
GBP
|
— | — | — | — | — |
42,200,000
GBP
|
77,300,000
GBP
|
— | — | — |
119,500,000
GBP
|
— | — | — | — | — | — |
| Other comprehensive income | — | — | — |
30,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
28,300,000
GBP
|
— | — | — | — | — | — |
| Comprehensive income | — |
–
GBP
|
30,000,000
GBP
|
51,900,000
GBP
|
81,900,000
GBP
|
— | — | — | — |
–
GBP
|
— | — | — | — |
28,300,000
GBP
|
— |
–
GBP
|
— | — | — |
–
GBP
|
— |
91,200,000
GBP
|
119,500,000
GBP
|
— | — | — | — | — |
| Dividends recognised as distributions to owners | — |
–
GBP
|
–
GBP
|
32,400,000
GBP
|
32,400,000
GBP
|
— | — | — | — |
–
GBP
|
— | — | — | — |
–
GBP
|
— |
–
GBP
|
— | — | — |
–
GBP
|
— |
30,800,000
GBP
|
30,800,000
GBP
|
— | — | — | — | — |
| Increase (decrease) through share-based payment transactions, equity | — |
–
GBP
|
200,000
GBP
|
200,000
GBP
|
–
GBP
|
— | — | — | — |
–
GBP
|
— | — | — | — |
300,000
GBP
|
— |
–
GBP
|
— | — | — |
–
GBP
|
— |
300,000
GBP
|
–
GBP
|
— | — | — | — | — |
| Increase (decrease) in equity | — |
–
GBP
|
26,700,000
GBP
|
109,900,000
GBP
|
136,600,000
GBP
|
— | — | — | — |
–
GBP
|
— | — | — | — |
28,600,000
GBP
|
— |
–
GBP
|
— | — | — |
–
GBP
|
— |
60,100,000
GBP
|
88,700,000
GBP
|
— | — | — | — | — |