Statement Of Comprehensive Income [Abstract]
| Concept |
2021-04-05 to 2022-04-04 |
2021-04-05 to 2022-04-04 |
2021-04-05 to 2022-04-04 |
2021-04-05 to 2022-04-04 |
2021-04-05 to 2022-04-04 |
2021-04-05 to 2022-04-04 |
2021-04-05 to 2022-04-04 |
2021-04-05 to 2022-04-04 |
2020-04-05 to 2021-04-04 |
2020-04-05 to 2021-04-04 |
2020-04-05 to 2021-04-04 |
2020-04-05 to 2021-04-04 |
2020-04-05 to 2021-04-04 |
2020-04-05 to 2021-04-04 |
2020-04-05 to 2021-04-04 |
2020-04-05 to 2021-04-04 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Statement of comprehensive income [abstract] | ||||||||||||||||
| Profit (loss) |
1,252,000,000
GBP
|
-
GBP
|
-
GBP
|
-
GBP
|
-
GBP
|
1,252,000,000
GBP
|
-
GBP
|
-
GBP
|
-
GBP
|
618,000,000
GBP
|
-
GBP
|
-
GBP
|
-
GBP
|
618,000,000
GBP
|
-
GBP
|
-
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) from investments in equity instruments | — | — | — | — | — |
10,000,000
GBP
|
— | — | — |
4,000,000
GBP
|
— | — | — | — | — | — |
| Other comprehensive income, before tax, gains (losses) on revaluation of property, plant and equipment, right-of-use assets and intangible assets | — | — | — | — | — |
7,000,000
GBP
|
— | — | — |
9,000,000
GBP
|
— | — | — | — | — | — |
| Other comprehensive income, before tax, gains (losses) on remeasurements of defined benefit plans | — | — | — | — | — |
836,000,000
GBP
|
— | — | — |
112,000,000
GBP
|
— | — | — | — | — | — |
| Components of other comprehensive income that will be reclassified to profit or loss, before tax [abstract] | ||||||||||||||||
| Cash flow hedges [abstract] | ||||||||||||||||
| Gains (losses) on cash flow hedges, before tax | — | — | — | — | — |
27,000,000
GBP
|
— | — | — |
98,000,000
GBP
|
— | — | — | — | — | — |
| Reclassification adjustments on cash flow hedges, before tax | — | — | — | — | — |
42,000,000
GBP
|
— | — | — |
54,000,000
GBP
|
— | — | — | — | — | — |
| Cost of hedging [abstract] | ||||||||||||||||
| Change in value of foreign currency basis spreads [abstract] | ||||||||||||||||
| Gains (losses) on change in value of foreign currency basis spreads, before tax | — | — | — | — | — |
8,000,000
GBP
|
— | — | — |
4,000,000
GBP
|
— | — | — | — | — | — |
| Reclassification adjustments on change in value of foreign currency basis spreads, before tax | — | — | — | — | — |
4,000,000
GBP
|
— | — | — |
2,000,000
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, before tax | — | — | — | — | — |
12,000,000
GBP
|
— | — | — |
215,000,000
GBP
|
— | — | — | — | — | — |
| Reclassification adjustments on financial assets measured at fair value through other comprehensive income, before tax | — | — | — | — | — |
48,000,000
GBP
|
— | — | — |
40,000,000
GBP
|
— | — | — | — | — | — |
| Income tax relating to components of other comprehensive income that will not be reclassified to profit or loss [abstract] | ||||||||||||||||
| Income tax relating to investments in equity instruments included in other comprehensive income | — | — | — | — | — |
2,000,000
GBP
|
— | — | — |
1,000,000
GBP
|
— | — | — | — | — | — |
| Income tax relating to changes in revaluation surplus of property, plant and equipment, right-of-use assets and intangible assets included in other comprehensive income | — | — | — | — | — |
2,000,000
GBP
|
— | — | — |
11,000,000
GBP
|
— | — | — | — | — | — |
| Income tax relating to remeasurements of defined benefit plans included in other comprehensive income | — | — | — | — | — |
293,000,000
GBP
|
— | — | — |
40,000,000
GBP
|
— | — | — | — | — | — |
| Income tax relating to components of other comprehensive income that will be reclassified to profit or loss [abstract] | ||||||||||||||||
| Income tax relating to cash flow hedges included in other comprehensive income | — | — | — | — | — |
4,000,000
GBP
|
— | — | — |
41,000,000
GBP
|
— | — | — | — | — | — |
| Income tax relating to change in value of foreign currency basis spreads included in other comprehensive income | — | — | — | — | — |
1,000,000
GBP
|
— | — | — |
2,000,000
GBP
|
— | — | — | — | — | — |
| Income tax relating to financial assets measured at fair value through other comprehensive income included in other comprehensive income | — | — | — | — | — |
8,000,000
GBP
|
— | — | — |
47,000,000
GBP
|
— | — | — | — | — | — |
| Other comprehensive income | — | — | — | — | — |
520,000,000
GBP
|
— | — | — |
54,000,000
GBP
|
— | — | — | — | — | — |
| Comprehensive income |
1,795,000,000
GBP
|
5,000,000
GBP
|
11,000,000
GBP
|
-
GBP
|
-
GBP
|
1,772,000,000
GBP
|
3,000,000
GBP
|
20,000,000
GBP
|
-
GBP
|
564,000,000
GBP
|
4,000,000
GBP
|
131,000,000
GBP
|
111,000,000
GBP
|
546,000,000
GBP
|
2,000,000
GBP
|
-
GBP
|