Subclassifications Of Assets, Liabilities And Equities [Abstract]
| Concept |
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 |
|---|---|---|---|---|---|---|
| Subclassifications of assets, liabilities and equities [abstract] | ||||||
| Property, plant and equipment [abstract] | ||||||
| Property, plant and equipment |
428,000,000
GBP
|
— | — |
768,000,000
GBP
|
— | — |
| Intangible assets and goodwill [abstract] | ||||||
| Intangible assets other than goodwill [abstract] | ||||||
| Intangible assets other than goodwill |
1,950,000,000
GBP
|
— | — |
2,434,000,000
GBP
|
— | — |
| Goodwill |
1,741,000,000
GBP
|
— | — |
1,799,000,000
GBP
|
— | — |
| Investment property [abstract] | ||||||
| Investment property |
7,003,000,000
GBP
|
— | — |
11,369,000,000
GBP
|
— | — |
| Investments accounted for using equity method [abstract] | ||||||
| Investments in associates accounted for using equity method |
118,000,000
GBP
|
— | — |
263,000,000
GBP
|
— | — |
| Investments in joint ventures accounted for using equity method |
1,855,000,000
GBP
|
— | — |
1,702,000,000
GBP
|
— | — |
| Trade and other receivables [abstract] | ||||||
| Trade and other receivables |
6,088,000,000
GBP
|
— | — |
9,352,000,000
GBP
|
— | — |
| Categories of financial assets [abstract] | ||||||
| Financial assets |
264,961,000,000
GBP
|
— | — |
351,378,000,000
GBP
|
— | — |
| Cash and cash equivalents [abstract] | ||||||
| Cash and cash equivalents |
12,485,000,000
GBP
|
— | — |
16,900,000,000
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 |
—
GBP
|
— | — |
17,733,000,000
GBP
|
— | — |
| Miscellaneous assets [abstract] | ||||||
| Net defined benefit asset |
2,769,000,000
GBP
|
— | — |
2,834,000,000
GBP
|
— | — |
| Borrowings [abstract] | ||||||
| Borrowings |
7,344,000,000
GBP
|
— | — |
9,684,000,000
GBP
|
— | — |
| Borrowings, by type [abstract] | ||||||
| Miscellaneous liabilities [abstract] | ||||||
| Investment contracts liabilities |
172,452,000,000
GBP
|
— | — |
222,831,000,000
GBP
|
— | — |
| Other liabilities |
2,959,000,000
GBP
|
— | — |
3,043,000,000
GBP
|
— | — |
| Issued capital [abstract] | ||||||
| Issued capital |
1,141,000,000
GBP
|
941,000,000
GBP
|
200,000,000
GBP
|
1,182,000,000
GBP
|
982,000,000
GBP
|
200,000,000
GBP
|
| Retained earnings [abstract] | ||||||
| Retained earnings |
7,556,000,000
GBP
|
— | — |
7,468,000,000
GBP
|
— | — |
| Accumulated other comprehensive income [abstract] | ||||||
| Reserve of exchange differences on translation |
314,000,000
GBP
|
— | — |
862,000,000
GBP
|
— | — |
| Miscellaneous equity [abstract] | ||||||
| Capital redemption reserve |
86,000,000
GBP
|
— | — |
44,000,000
GBP
|
— | — |
| Merger reserve |
8,974,000,000
GBP
|
— | — |
8,974,000,000
GBP
|
— | — |
| Capital reserve |
10,308,000,000
GBP
|
— | — |
10,260,000,000
GBP
|
— | — |
| Net assets (liabilities) [abstract] | ||||||
| Assets |
358,474,000,000
GBP
|
— | — |
479,857,000,000
GBP
|
— | — |
| Liabilities |
339,020,000,000
GBP
|
— | — |
459,297,000,000
GBP
|
— | — |
| Assets less current liabilities [abstract] |