Statement Of Cash Flows [Abstract]
| Concept |
2021-01-01 to 2021-12-31 |
2020-01-01 to 2020-12-31 |
|---|---|---|
| Statement of cash flows [abstract] | ||
| Cash flows from (used in) investing activities [abstract] | ||
| Purchase of interests in investments accounted for using equity method |
11,000,000
GBP
|
5,000,000
GBP
|
| Proceeds from sales of investments accounted for using equity method |
304,000,000
GBP
|
914,000,000
GBP
|
| Purchase of financial instruments, classified as investing activities |
368,000,000
GBP
|
521,000,000
GBP
|
| Proceeds from sales or maturity of financial instruments, classified as investing activities |
938,000,000
GBP
|
737,000,000
GBP
|
| Cash flows from (used in) financing activities [abstract] | ||
| Proceeds from issue of bonds, notes and debentures |
208,000,000
GBP
|
–
GBP
|