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 |
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 |
2019-01-01 to 2019-12-31 |
2019-01-01 to 2019-12-31 |
2019-01-01 to 2019-12-31 |
2019-01-01 to 2019-12-31 |
2019-01-01 to 2019-12-31 |
2019-01-01 to 2019-12-31 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of comprehensive income [abstract] | |||||||||||||||||||||
| Profit (loss) |
19,000,000
GBP
|
— |
1,365,000,000
GBP
|
— | — |
1,384,000,000
GBP
|
1,365,000,000
GBP
|
471,000,000
GBP
|
452,000,000
GBP
|
— | — | — |
19,000,000
GBP
|
452,000,000
GBP
|
— |
714,000,000
GBP
|
714,000,000
GBP
|
19,000,000
GBP
|
733,000,000
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 | — | — |
845,000,000
GBP
|
— | — |
845,000,000
GBP
|
845,000,000
GBP
|
372,000,000
GBP
|
370,000,000
GBP
|
— | — | — |
2,000,000
GBP
|
370,000,000
GBP
|
— |
393,000,000
GBP
|
393,000,000
GBP
|
2,000,000
GBP
|
391,000,000
GBP
|
— | — |
| Other comprehensive income, net of tax, change in fair value of financial liability attributable to change in credit risk of liability | — | — | — | — | — |
—
GBP
|
— |
3,000,000
GBP
|
3,000,000
GBP
|
— | — | — | — |
3,000,000
GBP
|
— |
58,000,000
GBP
|
58,000,000
GBP
|
— |
58,000,000
GBP
|
— | — |
| Other comprehensive income that will not be reclassified to profit or loss, net of tax | — | — | — | — | — |
845,000,000
GBP
|
— |
375,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
449,000,000
GBP
|
— | — |
| Components of other comprehensive income that will be reclassified to profit or loss, net of tax [abstract] | |||||||||||||||||||||
| Exchange differences on translation [abstract] | |||||||||||||||||||||
| Gains (losses) on exchange differences on translation of foreign operations, net of tax | — | — | — | — | — |
—
GBP
|
— |
—
GBP
|
— | — | — | — | — | — | — | — | — | — |
4,000,000
GBP
|
— | — |
| Other comprehensive income, net of tax, exchange differences on translation of foreign operations | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
4,000,000
GBP
|
4,000,000
GBP
|
— | — |
4,000,000
GBP
|
— | — |
| Cash flow hedges [abstract] | |||||||||||||||||||||
| Other comprehensive income, net of tax, cash flow hedges | — |
374,000,000
GBP
|
374,000,000
GBP
|
— | — |
374,000,000
GBP
|
— |
110,000,000
GBP
|
— | — |
110,000,000
GBP
|
— | — |
110,000,000
GBP
|
— |
115,000,000
GBP
|
— | — |
115,000,000
GBP
|
— |
115,000,000
GBP
|
| Financial assets measured at fair value through other comprehensive income [abstract] | |||||||||||||||||||||
| Gains (losses) on financial assets measured at fair value through other comprehensive income, net of tax | — | — |
3,000,000
GBP
|
— |
3,000,000
GBP
|
3,000,000
GBP
|
— |
5,000,000
GBP
|
— |
5,000,000
GBP
|
— | — | — |
5,000,000
GBP
|
— | — | — | — |
—
GBP
|
— | — |
| Other comprehensive income that will be reclassified to profit or loss, net of tax | — | — | — | — | — |
377,000,000
GBP
|
— |
115,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
111,000,000
GBP
|
— | — |
| Other comprehensive income | — | — | — | — | — |
468,000,000
GBP
|
— |
260,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
338,000,000
GBP
|
— | — |
| Comprehensive income |
19,000,000
GBP
|
374,000,000
GBP
|
1,833,000,000
GBP
|
—
GBP
|
3,000,000
GBP
|
1,852,000,000
GBP
|
2,210,000,000
GBP
|
211,000,000
GBP
|
79,000,000
GBP
|
5,000,000
GBP
|
110,000,000
GBP
|
—
GBP
|
17,000,000
GBP
|
194,000,000
GBP
|
4,000,000
GBP
|
374,000,000
GBP
|
263,000,000
GBP
|
21,000,000
GBP
|
395,000,000
GBP
|
—
GBP
|
115,000,000
GBP
|
| Comprehensive income attributable to [abstract] | |||||||||||||||||||||
| Comprehensive income, attributable to owners of parent | — | — | — | — | — |
1,833,000,000
GBP
|
— |
194,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
374,000,000
GBP
|
— | — |
| Comprehensive income, attributable to non-controlling interests | — | — | — | — | — |
19,000,000
GBP
|
— |
17,000,000
GBP
|
— | — | — | — | — | — | — | — | — | — |
21,000,000
GBP
|
— | — |