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 |
2019-01-01 to 2019-12-31 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of comprehensive income [abstract] | |||||||||||||||||
| Profit (loss) |
8 3 .0
GBP
|
−
GBP
|
−
GBP
|
−
GBP
|
−
GBP
|
6 3 7. 7
GBP
|
720. 7
GBP
|
6 3 7. 7
GBP
|
2,9 65.1
GBP
|
−
GBP
|
2,901,300,000
GBP
|
63. 8
GBP
|
−
GBP
|
2, 965.1
GBP
|
−
GBP
|
−
GBP
|
9 3 7. 9
GBP
|
| 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 |
−
GBP
|
−
GBP
|
−
GBP
|
−
GBP
|
−
GBP
|
14 .3
GBP
|
14 .3
GBP
|
14 .3
GBP
|
2,000,000
GBP
|
−
GBP
|
2 .0
GBP
|
–
GBP
|
−
GBP
|
2 .0
GBP
|
−
GBP
|
−
GBP
|
36,600,000
GBP
|
| Income tax relating to components of other comprehensive income that will not be reclassified to profit or loss [abstract] | |||||||||||||||||
| Income tax relating to remeasurements of defined benefit plans included in other comprehensive income |
−
GBP
|
−
GBP
|
−
GBP
|
−
GBP
|
−
GBP
|
3 .0
GBP
|
3 . 0
GBP
|
3,000,000
GBP
|
7. 4
GBP
|
−
GBP
|
7. 4
GBP
|
–
GBP
|
−
GBP
|
7. 4
GBP
|
−
GBP
|
−
GBP
|
6,400,000
GBP
|
| Other comprehensive income |
10. 3
GBP
|
−
GBP
|
−
GBP
|
7 9.9
GBP
|
−
GBP
|
97. 9
GBP
|
108,200,000
GBP
|
1 8 .0
GBP
|
118. 3
GBP
|
−
GBP
|
115. 3
GBP
|
3 .9
GBP
|
−
GBP
|
111. 4
GBP
|
6 .9
GBP
|
–
GBP
|
1, 080.7
GBP
|
| Comprehensive income |
72 .7
GBP
|
−
GBP
|
−
GBP
|
7 9. 9
GBP
|
−
GBP
|
5 3 9. 8
GBP
|
612 . 5
GBP
|
6 1 9. 7
GBP
|
3,083,400,000
GBP
|
−
GBP
|
3,0 16.6
GBP
|
5 9.9
GBP
|
−
GBP
|
3,076,500,000
GBP
|
6 .9
GBP
|
–
GBP
|
1 42 .8
GBP
|
| Comprehensive income attributable to [abstract] | |||||||||||||||||
| Comprehensive income, attributable to owners of parent | — | — | — | — | — | — |
5 3 9. 8
GBP
|
— | — | — |
3,076,500,000
GBP
|
— | — | — | — | — |
2 1 8 . 6
GBP
|
| Comprehensive income, attributable to non-controlling interests | — | — | — | — | — | — |
72 .7
GBP
|
— | — | — |
59. 9
GBP
|
— | — | — | — | — |
75,800,000
GBP
|