Statement Of Changes In Equity [Abstract]
| Concept |
2023-01-01 to 2023-12-31 |
As at 2023-12-31 |
2023-01-01 to 2023-12-31 |
As at 2023-12-31 |
As at 2023-12-31 |
2023-01-01 to 2023-12-31 |
2023-01-01 to 2023-12-31 |
As at 2023-12-31 |
2023-01-01 to 2023-12-31 |
As at 2023-12-31 |
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 |
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 |
As at 2021-12-31 |
As at 2021-12-31 |
As at 2021-12-31 |
As at 2021-12-31 |
As at 2021-12-31 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of changes in equity [abstract] | |||||||||||||||||||||||||
| Statement of changes in equity [line items] | |||||||||||||||||||||||||
| Equity | — |
929,200,000
GBP
|
— |
728,400,000
GBP
|
106,700,000
GBP
|
— | — |
83,100,000
GBP
|
— |
11,000,000
GBP
|
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
|
| Changes in equity [abstract] | |||||||||||||||||||||||||
| Comprehensive income [abstract] | |||||||||||||||||||||||||
| Profit (loss) |
249,800,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — |
81,900,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Other comprehensive income |
10,700,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — |
30,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Comprehensive income |
260,500,000
GBP
|
— |
10,700,000
GBP
|
— | — |
249,800,000
GBP
|
–
GBP
|
— |
–
GBP
|
— | — |
–
GBP
|
30,000,000
GBP
|
51,900,000
GBP
|
81,900,000
GBP
|
— | — | — | — |
–
GBP
|
— | — | — | — | — |
| Dividends recognised as distributions to owners |
31,600,000
GBP
|
— |
–
GBP
|
— | — |
31,600,000
GBP
|
–
GBP
|
— |
–
GBP
|
— | — |
–
GBP
|
–
GBP
|
32,400,000
GBP
|
32,400,000
GBP
|
— | — | — | — |
–
GBP
|
— | — | — | — | — |
| Increase (decrease) through share-based payment transactions, equity |
500,000
GBP
|
— |
500,000
GBP
|
— | — |
–
GBP
|
–
GBP
|
— |
–
GBP
|
— | — |
–
GBP
|
200,000
GBP
|
200,000
GBP
|
–
GBP
|
— | — | — | — |
–
GBP
|
— | — | — | — | — |
| Increase (decrease) in equity |
291,600,000
GBP
|
— |
8,700,000
GBP
|
— | — |
282,900,000
GBP
|
–
GBP
|
— |
–
GBP
|
— | — |
–
GBP
|
26,700,000
GBP
|
109,900,000
GBP
|
136,600,000
GBP
|
— | — | — | — |
–
GBP
|
— | — | — | — | — |