Statement Of Comprehensive Income [Abstract]
| Concept |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
2021-01-01 to 2021-12-31 |
2020-01-01 to 2020-12-31 |
2020-01-01 to 2020-12-31 |
2020-01-01 to 2020-12-31 |
2020-01-01 to 2020-12-31 |
2020-01-01 to 2020-12-31 |
2020-01-01 to 2020-12-31 |
2020-01-01 to 2020-12-31 |
2020-01-01 to 2020-12-31 |
2020-01-01 to 2020-12-31 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of comprehensive income [abstract] | ||||||||||||||||||
| Profit (loss) |
9,000,000
GBP
|
–
GBP
|
–
GBP
|
–
GBP
|
–
GBP
|
–
GBP
|
83,000,000
GBP
|
92,000,000
GBP
|
83,000,000
GBP
|
1 ,1 3 8
GBP
|
–
GBP
|
1 ,1 4 2
GBP
|
4,000,000
GBP
|
–
GBP
|
1 ,1 3 8
GBP
|
–
GBP
|
–
GBP
|
–
GBP
|
| Other comprehensive income [abstract] | ||||||||||||||||||
| Components of other comprehensive income that will not be reclassified to profit or loss, net of tax [abstract] | ||||||||||||||||||
| Other comprehensive income, net of tax, gains (losses) on remeasurements of defined benefit plans | — | — | — | — | — | — | — |
52,000,000
GBP
|
— | — | — |
9 4
GBP
|
— | — | — | — | — | — |
| Other comprehensive income that will not be reclassified to profit or loss, net of tax | — | — | — | — | — | — | — |
50,000,000
GBP
|
— | — | — |
8 1
GBP
|
— | — | — | — | — | — |
| Components of other comprehensive income that will be reclassified to profit or loss, net of tax [abstract] | ||||||||||||||||||
| Exchange differences on translation [abstract] | ||||||||||||||||||
| Other comprehensive income, net of tax, exchange differences on translation of foreign operations | — | — | — | — | — | — | — |
1 3
GBP
|
— | — | — |
3,000,000
GBP
|
— | — | — | — | — | — |
| Other comprehensive income that will be reclassified to profit or loss, net of tax | — | — | — | — | — | — | — |
1 3
GBP
|
— | — | — |
3,000,000
GBP
|
— | — | — | — | — | — |
| Other comprehensive income |
–
GBP
|
–
GBP
|
–
GBP
|
–
GBP
|
1 3
GBP
|
–
GBP
|
37,000,000
GBP
|
37,000,000
GBP
|
50,000,000
GBP
|
81,000,000
GBP
|
–
GBP
|
7 8
GBP
|
–
GBP
|
–
GBP
|
78,000,000
GBP
|
–
GBP
|
3,000,000
GBP
|
–
GBP
|
| Comprehensive income |
9,000,000
GBP
|
–
GBP
|
–
GBP
|
–
GBP
|
1 3
GBP
|
–
GBP
|
120,000,000
GBP
|
129,000,000
GBP
|
133,000,000
GBP
|
1,057,000,000
GBP
|
–
GBP
|
1,06 4
GBP
|
4,000,000
GBP
|
–
GBP
|
1,06 0
GBP
|
–
GBP
|
3,000,000
GBP
|
–
GBP
|
| Comprehensive income attributable to [abstract] | ||||||||||||||||||
| Comprehensive income, attributable to owners of parent | — | — | — | — | — | — | — |
120,000,000
GBP
|
— | — | — |
1,06 0
GBP
|
— | — | — | — | — | — |
| Comprehensive income, attributable to non-controlling interests | — | — | — | — | — | — | — |
9,000,000
GBP
|
— | — | — |
4,000,000
GBP
|
— | — | — | — | — | — |