Statement Of Financial Position [Abstract]
| Concept |
As at 2023-12-31 |
As at 2023-12-31 |
As at 2023-12-31 |
As at 2023-12-31 |
As at 2023-12-31 |
As at 2023-12-31 |
As at 2023-12-31 |
As at 2022-12-31 |
As at 2022-12-31 |
As at 2022-12-31 |
As at 2022-12-31 |
As at 2022-12-31 |
As at 2022-12-31 |
As at 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 |
As at 2021-12-31 |
As at 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 |
As at 2020-12-31 |
As at 2020-12-31 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of financial position [abstract] | ||||||||||||||||||||||||||||
| Assets [abstract] | ||||||||||||||||||||||||||||
| Property, plant and equipment |
1,780,000,000
GBP
|
— | — | — | — | — | — |
1,757,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Right-of-use assets |
122,000,000
GBP
|
— | — | — | — | — | — |
142,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Deferred tax assets |
265,000,000
GBP
|
— | — | — | — | — | — |
220,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Cash and cash equivalents |
1,044,000,000
GBP
|
— | — | — | — | — | — |
684,000,000
GBP
|
— | — | — | — | — | — | — | — |
414,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
| Assets |
34,055,000,000
GBP
|
— | — | — | — | — | — |
34,815,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Equity and liabilities [abstract] | ||||||||||||||||||||||||||||
| Equity [abstract] | ||||||||||||||||||||||||||||
| Issued capital |
92,000,000
GBP
|
— | — | — | — | — | — |
92,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Retained earnings |
27,474,000,000
GBP
|
— | — | — | — | — | — |
26,730,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Other reserves |
10,960,000,000
GBP
|
— | — | — | — | — | — |
10,491,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Equity attributable to owners of parent |
16,606,000,000
GBP
|
— | — | — | — | — | — |
16,331,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Non-controlling interests |
123,000,000
GBP
|
— | — | — | — | — | — |
126,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Equity |
16,729,000,000
GBP
|
27,474,000,000
GBP
|
10,960,000,000
GBP
|
123,000,000
GBP
|
—
GBP
|
92,000,000
GBP
|
16,606,000,000
GBP
|
16,457,000,000
GBP
|
10,491,000,000
GBP
|
126,000,000
GBP
|
—
GBP
|
26,730,000,000
GBP
|
92,000,000
GBP
|
16,331,000,000
GBP
|
37,538,000,000
GBP
|
11,184,000,000
GBP
|
26,480,000,000
GBP
|
26,355,000,000
GBP
|
125,000,000
GBP
|
—
GBP
|
1,000,000
GBP
|
37,281,000,000
GBP
|
111,000,000
GBP
|
26,112,000,000
GBP
|
1,000,000
GBP
|
11,170,000,000
GBP
|
—
GBP
|
26,223,000,000
GBP
|
| Liabilities [abstract] | ||||||||||||||||||||||||||||
| Deferred tax liabilities |
3,487,000,000
GBP
|
— | — | — | — | — | — |
3,601,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Liabilities |
17,326,000,000
GBP
|
— | — | — | — | — | — |
18,358,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |