Subclassifications Of Assets, Liabilities And Equities [Abstract]
| Concept |
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 2022-06-15 |
As at 2021-12-31 |
As at 2021-12-31 |
As at 2021-12-31 |
|---|---|---|---|---|---|---|---|---|---|---|
| Subclassifications of assets, liabilities and equities [abstract] | ||||||||||
| Property, plant and equipment [abstract] | ||||||||||
| Property, plant and equipment |
424,000,000
GBP
|
— | — |
350,000,000
GBP
|
— | — | — |
428,000,000
GBP
|
— | — |
| Intangible assets and goodwill [abstract] | ||||||||||
| Intangible assets other than goodwill [abstract] | ||||||||||
| Intangible assets other than goodwill |
968,000,000
GBP
|
— | — |
940,000,000
GBP
|
— | — | — |
994,000,000
GBP
|
— | — |
| Goodwill |
2,100,000,000
GBP
|
— | — |
2,102,000,000
GBP
|
— | — | — |
1,741,000,000
GBP
|
— | — |
| Investment property [abstract] | ||||||||||
| Investment property |
6,232,000,000
GBP
|
— | — |
5,899,000,000
GBP
|
— | — | — |
7,003,000,000
GBP
|
— | — |
| Investments accounted for using equity method [abstract] | ||||||||||
| Investments in associates accounted for using equity method |
160,000,000
GBP
|
— | — |
41,000,000
GBP
|
— | — | — |
118,000,000
GBP
|
— | — |
| Investments in joint ventures accounted for using equity method |
1,189,000,000
GBP
|
— | — |
1,872,000,000
GBP
|
— | — | — |
1,784,000,000
GBP
|
— | — |
| Trade and other receivables [abstract] | ||||||||||
| Trade and other receivables |
3,721,000,000
GBP
|
— | — |
3,480,000,000
GBP
|
— | — | — |
3,740,000,000
GBP
|
— | — |
| Categories of financial assets [abstract] | ||||||||||
| Financial assets |
245,831,000,000
GBP
|
— | — |
224,086,000,000
GBP
|
— | — | — |
264,961,000,000
GBP
|
— | — |
| Cash and cash equivalents [abstract] | ||||||||||
| Cash and cash equivalents |
17,273,000,000
GBP
|
— | — |
22,505,000,000
GBP
|
— | — | — |
12,485,000,000
GBP
|
— | — |
| Non-current assets or disposal groups classified as held for sale or as held for distribution to owners [abstract] | ||||||||||
| Non-current assets or disposal groups classified as held for sale or as held for distribution to owners |
748,000,000
GBP
|
— | — |
—
GBP
|
— | — | — |
—
GBP
|
— | — |
| Miscellaneous assets [abstract] | ||||||||||
| Net defined benefit asset |
862,000,000
GBP
|
— | — |
1,234,000,000
GBP
|
— | — | — |
2,769,000,000
GBP
|
— | — |
| Borrowings [abstract] | ||||||||||
| Borrowings |
6,374,000,000
GBP
|
— | — |
6,755,000,000
GBP
|
— | — |
500,000,000
GBP
|
7,344,000,000
GBP
|
— | — |
| Borrowings, by type [abstract] | ||||||||||
| Notes and debentures issued |
496,000,000
GBP
|
— | — |
496,000,000
GBP
|
— | — | — |
—
GBP
|
— | — |
| Miscellaneous liabilities [abstract] | ||||||||||
| Other liabilities |
3,289,000,000
GBP
|
— | — |
2,567,000,000
GBP
|
— | — | — |
2,545,000,000
GBP
|
— | — |
| Issued capital [abstract] | ||||||||||
| Issued capital |
1,101,000,000
GBP
|
200,000,000
GBP
|
901,000,000
GBP
|
1,124,000,000
GBP
|
924,000,000
GBP
|
200,000,000
GBP
|
— |
1,141,000,000
GBP
|
941,000,000
GBP
|
200,000,000
GBP
|
| Retained earnings [abstract] | ||||||||||
| Retained earnings |
2,228,000,000
GBP
|
— | — |
2,328,000,000
GBP
|
— | — | — |
4,792,000,000
GBP
|
— | — |
| Miscellaneous equity [abstract] | ||||||||||
| Capital redemption reserve |
24,000,000
GBP
|
— | — |
3,855,000,000
GBP
|
— | — | — |
86,000,000
GBP
|
— | — |
| Merger reserve |
5,224,000,000
GBP
|
— | — |
5,224,000,000
GBP
|
— | — | — |
8,974,000,000
GBP
|
— | — |
| Capital reserve |
5,265,000,000
GBP
|
— | — |
10,342,000,000
GBP
|
— | — | — |
10,308,000,000
GBP
|
— | — |
| Net assets (liabilities) [abstract] | ||||||||||
| Assets |
328,843,000,000
GBP
|
— | — |
309,583,000,000
GBP
|
— | — | — |
351,924,000,000
GBP
|
— | — |
| Liabilities |
319,243,000,000
GBP
|
— | — |
299,369,000,000
GBP
|
— | — | — |
335,234,000,000
GBP
|
— | — |
| Assets less current liabilities [abstract] |