Statement Of Changes In Equity [Abstract]
| Concept |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
2021-12-16 to 2021-12-16 |
2021-08-12 to 2021-08-12 |
2020-01-01 to 2020-12-31 |
2020-01-01 to 2020-12-31 |
2020-01-01 to 2020-12-31 |
2020-01-01 to 2020-12-31 |
2020-01-01 to 2020-12-31 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of changes in equity [abstract] | |||||||||||||
| Statement of changes in equity [line items] | |||||||||||||
| Dividends recognised as distributions to non-controlling interests |
60,000,000
GBP
|
— | — | — |
60,000,000
GBP
|
— | — | — | — |
30,000,000
GBP
|
— |
30,000,000
GBP
|
— |
| Increase (decrease) through disposal of subsidiary, equity |
722,000,000
GBP
|
183,000,000
GBP
|
327,000,000
GBP
|
144,000,000
GBP
|
866,000,000
GBP
|
—
GBP
|
— | — |
—
GBP
|
199,000,000
GBP
|
173,000,000
GBP
|
26,000,000
GBP
|
173,000,000
GBP
|
| Increase (decrease) through transfer between revaluation surplus and retained earnings, equity | — |
9,000,000
GBP
|
— | — |
—
GBP
|
9,000,000
GBP
|
— | — | — | — | — | — | — |
| Purchase of treasury shares | — | — | — | — | — | — |
1,000,000,000
GBP
|
750,000,000
GBP
|
— | — | — | — | — |
| Cancellation of treasury shares | — | — | — | — |
42,000,000
GBP
|
— | — | — | — | — | — | — | — |