Statement Of Changes In Net Assets Available For Benefits [Abstract]
| Concept |
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 |
|---|---|---|---|---|---|---|
| Statement of changes in net assets available for benefits [abstract] | ||||||
| Reconciliation of changes in net assets available for benefits [abstract] | ||||||
| Changes in net assets available for benefits [abstract] | ||||||
| Investment income |
—
GBP
|
5 3 .7
GBP
|
5 3 .7
GBP
|
—
GBP
|
89. 0
GBP
|
8 9.0
GBP
|
| Tax expense (income) |
—
GBP
|
2 .9
GBP
|
2 .9
GBP
|
—
GBP
|
0 .2
GBP
|
0 .2
GBP
|