Subclassifications Of Assets, Liabilities And Equities [Abstract]
| Concept |
As at 2023-12-31 |
As at 2022-12-31 |
As at 2022-01-01 |
As at 2021-12-31 |
|---|---|---|---|---|
| Subclassifications of assets, liabilities and equities [abstract] | ||||
| Property, plant and equipment [abstract] | ||||
| Property, plant and equipment |
90,100,000
GBP
|
89,800,000
GBP
|
103,200,000
GBP
|
— |
| Intangible assets and goodwill [abstract] | ||||
| Intangible assets and goodwill |
242,900,000
GBP
|
217,600,000
GBP
|
151,800,000
GBP
|
— |
| Trade and other receivables [abstract] | ||||
| Other receivables |
409,900,000
GBP
|
316,400,000
GBP
|
391,500,000
GBP
|
— |
| Cash and cash equivalents [abstract] | ||||
| Cash and cash equivalents |
353,100,000
GBP
|
297,000,000
GBP
|
372,700,000
GBP
|
372,700,000
GBP
|
| Miscellaneous assets [abstract] | ||||
| Investments other than investments accounted for using equity method |
3,862,400,000
GBP
|
3,411,200,000
GBP
|
3,742,600,000
GBP
|
— |
| Loans and advances | — | — | — | — |
| Loans and advances to customers |
879,400,000
GBP
|
823,900,000
GBP
|
556,800,000
GBP
|
— |
| Trade and other payables [abstract] | ||||
| Trade and other payables |
305,800,000
GBP
|
254,900,000
GBP
|
351,200,000
GBP
|
— |
| Issued capital [abstract] | ||||
| Issued capital |
300,000
GBP
|
300,000
GBP
|
300,000
GBP
|
— |
| Retained earnings [abstract] | ||||
| Retained earnings |
1,018,900,000
GBP
|
922,600,000
GBP
|
1,243,500,000
GBP
|
— |
| Net assets (liabilities) [abstract] | ||||
| Assets |
7,096,200,000
GBP
|
6,208,800,000
GBP
|
6,336,700,000
GBP
|
— |
| Liabilities |
6,103,400,000
GBP
|
5,321,800,000
GBP
|
5,053,800,000
GBP
|
— |
| Assets less current liabilities [abstract] |