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 |
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] | ||||||||||||||||
| Other comprehensive income [abstract] | ||||||||||||||||
| Components of other comprehensive income that will not be reclassified to profit or loss, before tax [abstract] | ||||||||||||||||
| Other comprehensive income, before tax, gains (losses) on remeasurements of defined benefit plans | — | — | — | — | — | — |
2,600,000
GBP
|
— | — | — | — |
300,000
GBP
|
— | — | — | — |
| Income tax relating to components of other comprehensive income that will not be reclassified to profit or loss [abstract] | ||||||||||||||||
| Income tax relating to components of other comprehensive income that will not be reclassified to profit or loss | — | — | — | — | — | — |
800,000
GBP
|
— | — | — | — |
100,000
GBP
|
— | — | — | — |
| Other comprehensive income |
–
GBP
|
–
GBP
|
–
GBP
|
–
GBP
|
6,000,000
GBP
|
–
GBP
|
7,800,000
GBP
|
1,800,000
GBP
|
200,000
GBP
|
–
GBP
|
–
GBP
|
700,000
GBP
|
–
GBP
|
900,000
GBP
|
–
GBP
|
–
GBP
|
| Comprehensive income |
–
GBP
|
–
GBP
|
–
GBP
|
–
GBP
|
6,000,000
GBP
|
–
GBP
|
16,600,000
GBP
|
22,600,000
GBP
|
20,500,000
GBP
|
–
GBP
|
–
GBP
|
19,600,000
GBP
|
–
GBP
|
900,000
GBP
|
–
GBP
|
–
GBP
|
| Comprehensive income attributable to [abstract] | ||||||||||||||||
| Comprehensive income, attributable to owners of parent | — | — | — | — | — | — |
16,600,000
GBP
|
— | — | — | — |
19,600,000
GBP
|
— | — | — | — |