Statement Of Comprehensive Income [Abstract]
| Concept |
2023-01-01 to 2023-12-31 |
2023-01-01 to 2023-12-31 |
2023-01-01 to 2023-12-31 |
2023-01-01 to 2023-12-31 |
2023-01-01 to 2023-12-31 |
2023-01-01 to 2023-12-31 |
2023-01-01 to 2023-12-31 |
2023-01-01 to 2023-12-31 |
2023-01-01 to 2023-12-31 |
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 |
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 |
2022-01-01 to 2022-12-31 |
2022-01-01 to 2022-12-31 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of comprehensive income [abstract] | |||||||||||||||||||
| Profit (loss) |
—
GBP
|
309,000,000
GBP
|
297,000,000
GBP
|
—
GBP
|
12,000,000
GBP
|
297,000,000
GBP
|
—
GBP
|
—
GBP
|
—
GBP
|
—
GBP
|
—
GBP
|
—
GBP
|
2,055,000,000
GBP
|
2,068,000,000
GBP
|
13,000,000
GBP
|
2,068,000,000
GBP
|
—
GBP
|
2,055,000,000
GBP
|
—
GBP
|
| Other comprehensive income [abstract] | |||||||||||||||||||
| Components of other comprehensive income that will not be reclassified to profit or loss, before tax [abstract] | |||||||||||||||||||
| Other comprehensive income, before tax, gains (losses) on remeasurements of defined benefit plans | — |
124,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
29,000,000
GBP
|
— |
| Income tax relating to components of other comprehensive income that will not be reclassified to profit or loss [abstract] | |||||||||||||||||||
| Income tax relating to remeasurements of defined benefit plans included in other comprehensive income | — |
28,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
7,000,000
GBP
|
— |
| Other comprehensive income |
—
GBP
|
108,000,000
GBP
|
104,000,000
GBP
|
8,000,000
GBP
|
4,000,000
GBP
|
96,000,000
GBP
|
—
GBP
|
—
GBP
|
—
GBP
|
—
GBP
|
—
GBP
|
20,000,000
GBP
|
42,000,000
GBP
|
22,000,000
GBP
|
—
GBP
|
42,000,000
GBP
|
—
GBP
|
42,000,000
GBP
|
—
GBP
|
| Comprehensive income |
—
GBP
|
201,000,000
GBP
|
193,000,000
GBP
|
8,000,000
GBP
|
8,000,000
GBP
|
201,000,000
GBP
|
—
GBP
|
—
GBP
|
—
GBP
|
—
GBP
|
—
GBP
|
20,000,000
GBP
|
2,013,000,000
GBP
|
2,046,000,000
GBP
|
13,000,000
GBP
|
2,026,000,000
GBP
|
—
GBP
|
2,013,000,000
GBP
|
—
GBP
|
| Comprehensive income attributable to [abstract] | |||||||||||||||||||
| Comprehensive income, attributable to owners of parent | — |
193,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
2,026,000,000
GBP
|
— |
| Comprehensive income, attributable to non-controlling interests | — |
8,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
13,000,000
GBP
|
— |