Statement Of Cash Flows [Abstract]
| Concept |
2023-01-01 to 2023-12-31 |
2023-01-01 to 2023-12-31 |
2023-01-01 to 2023-12-31 |
As at 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 |
As at 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 cash flows [abstract] | ||||||||||||||||||||
| Cash flows from (used in) operating activities [abstract] | ||||||||||||||||||||
| Profit (loss) |
12,000,000
GBP
|
–
GBP
|
11,000,000
GBP
|
— |
–
GBP
|
1,000,000
GBP
|
–
GBP
|
1,000,000
GBP
|
–
GBP
|
–
GBP
|
— |
–
GBP
|
546,000,000
GBP
|
–
GBP
|
1,000,000
GBP
|
558,000,000
GBP
|
11,000,000
GBP
|
–
GBP
|
558,000,000
GBP
|
–
GBP
|
| Dividends received, classified as operating activities |
91,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
110,000,000
GBP
|
— | — | — | — | — | — | — |
| Interest paid, classified as operating activities |
3,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
–
GBP
|
— | — | — | — | — | — | — |
| Interest received, classified as operating activities |
85,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
38,000,000
GBP
|
— | — | — | — | — | — | — |
| Income taxes paid (refund), classified as operating activities |
34,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
36,000,000
GBP
|
— | — | — | — | — | — | — |
| Cash flows from (used in) operating activities |
221,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
110,000,000
GBP
|
— | — | — | — | — | — | — |
| Cash flows from (used in) investing activities [abstract] | ||||||||||||||||||||
| Cash flows from losing control of subsidiaries or other businesses, classified as investing activities |
139,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
–
GBP
|
— | — | — | — | — | — | — |
| Cash flows used in obtaining control of subsidiaries or other businesses, classified as investing activities |
108,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
1,378,000,000
GBP
|
— | — | — | — | — | — | — |
| Purchase of property, plant and equipment, classified as investing activities |
18,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
21,000,000
GBP
|
— | — | — | — | — | — | — |
| Purchase of intangible assets, classified as investing activities |
41,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
6,000,000
GBP
|
— | — | — | — | — | — | — |
| Cash flows from (used in) investing activities |
542,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
86,000,000
GBP
|
— | — | — | — | — | — | — |
| Cash flows from (used in) financing activities [abstract] | ||||||||||||||||||||
| Payments to acquire or redeem entity's shares |
302,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
302,000,000
GBP
|
— | — | — | — | — | — | — |
| Dividends paid, classified as financing activities |
279,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
307,000,000
GBP
|
— | — | — | — | — | — | — |
| Cash flows from (used in) financing activities |
711,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
761,000,000
GBP
|
— | — | — | — | — | — | — |
| Increase (decrease) in cash and cash equivalents before effect of exchange rate changes |
52,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
737,000,000
GBP
|
— | — | — | — | — | — | — |
| Effect of exchange rate changes on cash and cash equivalents [abstract] | ||||||||||||||||||||
| Effect of exchange rate changes on cash and cash equivalents |
8,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — | — |
28,000,000
GBP
|
— | — | — | — | — | — | — |
| Cash and cash equivalents | — | — | — |
1,196,000,000
GBP
|
— | — | — | — | — | — |
1 ,133
GBP
|
— | — | — | — | — | — | — | — | — |