Statement Of Changes In Equity [Abstract]
| Concept |
As at 2021-12-31 |
2021-01-01 to 2021-12-31 |
As at 2021-12-31 |
As at 2021-12-31 |
2021-01-01 to 2021-12-31 |
As at 2021-12-31 |
As at 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 |
2021-01-01 to 2021-12-31 |
2020-01-01 to 2020-12-31 |
As at 2020-12-31 |
2020-01-01 to 2020-12-31 |
2020-01-01 to 2020-12-31 |
As at 2020-12-31 |
As at 2020-12-31 |
2020-01-01 to 2020-12-31 |
As at 2020-12-31 |
2020-01-01 to 2020-12-31 |
As at 2020-12-31 |
2020-01-01 to 2020-12-31 |
As at 2020-12-31 |
As at 2019-12-31 |
As at 2019-12-31 |
As at 2019-12-31 |
As at 2019-12-31 |
As at 2019-12-31 |
As at 2019-12-31 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of changes in equity [abstract] | ||||||||||||||||||||||||||||||
| Statement of changes in equity [line items] | ||||||||||||||||||||||||||||||
| Equity |
3 , 0 55 .1
GBP
|
— |
23 6.5
GBP
|
3,625. 2
GBP
|
— |
276. 8
GBP
|
24 . 9
GBP
|
— | — |
31,900,000
GBP
|
— | — | — |
2 ,950. 9
GBP
|
— | — |
236,500,000
GBP
|
31,900,000
GBP
|
— |
22 .3
GBP
|
— |
3 , 51 8 .4
GBP
|
— |
276 .8
GBP
|
236,500,000
GBP
|
276 . 8
GBP
|
1 9.2
GBP
|
3 , 258 . 3
GBP
|
2, 693. 9
GBP
|
3 1.9
GBP
|
| Changes in equity [abstract] | ||||||||||||||||||||||||||||||
| Comprehensive income [abstract] | ||||||||||||||||||||||||||||||
| Profit (loss) | — |
–
GBP
|
— | — |
–
GBP
|
— | — |
–
GBP
|
–
GBP
|
— |
7 8 7. 2
GBP
|
7 8 7. 2
GBP
|
638,400,000
GBP
|
— |
–
GBP
|
–
GBP
|
— | — |
638,400,000
GBP
|
— |
–
GBP
|
— |
–
GBP
|
— | — | — | — | — | — | — |
| Other comprehensive income | — |
–
GBP
|
— | — |
–
GBP
|
— | — |
–
GBP
|
–
GBP
|
— |
58,500,000
GBP
|
58,500,000
GBP
|
36,000,000
GBP
|
— |
–
GBP
|
–
GBP
|
— | — |
36. 0
GBP
|
— |
–
GBP
|
— |
–
GBP
|
— | — | — | — | — | — | — |
| Comprehensive income | — | — | — | — | — | — | — | — | — | — |
8 45 .7
GBP
|
— |
602,400,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Issue of equity | — |
–
GBP
|
— | — |
2,600,000
GBP
|
— | — |
–
GBP
|
–
GBP
|
— |
2,600,000
GBP
|
–
GBP
|
3,100,000
GBP
|
— |
–
GBP
|
–
GBP
|
— | — |
–
GBP
|
— |
–
GBP
|
— |
3 .1
GBP
|
— | — | — | — | — | — | — |
| Dividends recognised as distributions to owners | — |
–
GBP
|
— | — |
–
GBP
|
— | — |
–
GBP
|
–
GBP
|
— |
749,600,000
GBP
|
749,600,000
GBP
|
3 50.7
GBP
|
— |
–
GBP
|
–
GBP
|
— | — |
3 50.7
GBP
|
— |
–
GBP
|
— |
–
GBP
|
— | — | — | — | — | — | — |
| Increase (decrease) through share-based payment transactions, equity | — |
–
GBP
|
— | — |
–
GBP
|
— | — |
–
GBP
|
–
GBP
|
— |
8 .1
GBP
|
8 .1
GBP
|
7. 7
GBP
|
— |
–
GBP
|
–
GBP
|
— | — |
7. 7
GBP
|
— |
–
GBP
|
— |
–
GBP
|
— | — | — | — | — | — | — |