Statement Of Cash Flows [Abstract]
| Concept |
As at 2021-12-31 |
2021-01-01 to 2021-12-31 |
As at 2020-12-31 |
2020-01-01 to 2020-12-31 |
As at 2019-12-31 |
|---|---|---|---|---|---|
| Statement of cash flows [abstract] | |||||
| Cash flows from (used in) operating activities [abstract] | |||||
| Dividends received, classified as operating activities | — |
2 ,066
GBP
|
— |
1,70 4
GBP
|
— |
| Interest received, classified as operating activities | — |
2 ,1 8 9
GBP
|
— |
2, 282
GBP
|
— |
| Income taxes paid (refund), classified as operating activities | — |
3 1 5
GBP
|
— |
6 3 3
GBP
|
— |
| Cash flows from (used in) operating activities | — |
1,308,000,000
GBP
|
— |
2 , 576
GBP
|
— |
| Cash flows from (used in) investing activities [abstract] | |||||
| Proceeds from sales of property, plant and equipment, classified as investing activities | — |
4 1
GBP
|
— |
–
GBP
|
— |
| Purchase of property, plant and equipment, classified as investing activities | — |
7 7 0
GBP
|
— |
8 2 1
GBP
|
— |
| Cash flows from (used in) investing activities | — |
4 6 6
GBP
|
— |
9 5 7
GBP
|
— |
| Cash flows from (used in) financing activities [abstract] | |||||
| Payments to acquire or redeem entity's shares | — |
–
GBP
|
— |
1 0 5
GBP
|
— |
| Payments of lease liabilities, classified as financing activities | — |
3 5
GBP
|
— |
2 4
GBP
|
— |
| Dividends paid, classified as financing activities | — |
4 6 6
GBP
|
— |
5 6 2
GBP
|
— |
| Interest paid, classified as financing activities | — |
1 8 6
GBP
|
— |
1 8 9
GBP
|
— |
| Cash flows from (used in) financing activities | — |
6 8 7
GBP
|
— |
88 0
GBP
|
— |
| Increase (decrease) in cash and cash equivalents before effect of exchange rate changes | — |
155,000,000
GBP
|
— |
739,000,000
GBP
|
— |
| Effect of exchange rate changes on cash and cash equivalents [abstract] | |||||
| Effect of exchange rate changes on cash and cash equivalents | — |
23,000,000
GBP
|
— |
9,000,000
GBP
|
— |
| Cash and cash equivalents |
6 ,908
GBP
|
— |
6 ,7 7 6
GBP
|
— |
6,04 6
GBP
|