Statement Of Changes In Equity [Abstract]

Grainger PLC - Filing #1958617

Concept	2022-10-01 to 2023-09-30	As at 2023-09-30	2022-10-01 to 2023-09-30	2022-10-01 to 2023-09-30	As at 2023-09-30	2022-10-01 to 2023-09-30	As at 2023-09-30	As at 2023-09-30	2022-10-01 to 2023-09-30	As at 2023-09-30	2022-10-01 to 2023-09-30	As at 2023-09-30	As at 2023-09-30	2022-10-01 to 2023-09-30	As at 2022-09-30	As at 2022-09-30	2021-10-01 to 2022-09-30	2021-10-01 to 2022-09-30	As at 2022-09-30	2021-10-01 to 2022-09-30	As at 2022-09-30	2021-10-01 to 2022-09-30	As at 2022-09-30	As at 2022-09-30	2021-10-01 to 2022-09-30	2021-10-01 to 2022-09-30	2021-10-01 to 2022-09-30	As at 2022-09-30	As at 2021-09-30	As at 2021-09-30	As at 2021-09-30	As at 2021-09-30	As at 2021-09-30	As at 2021-09-30	As at 2021-09-30
Statement of changes in equity [abstract]
Statement of changes in equity [line items]
Equity	—	20,000,000 GBP	—	—	20,100,000 GBP	—	1,033,200,000 GBP	817,800,000 GBP	—	37,200,000 GBP	—	1,928,600,000 GBP	300,000 GBP	—	32,100,000 GBP	20,100,000 GBP	—	—	817,600,000 GBP	—	1,966,800,000 GBP	—	1,059,600,000 GBP	37,100,000 GBP	—	—	—	300,000 GBP	3,300,000 GBP	20,100,000 GBP	300,000 GBP	867,500,000 GBP	1,739,000,000 GBP	37,100,000 GBP	817,300,000 GBP
Changes in equity [abstract]
Comprehensive income [abstract]
Profit (loss)	– GBP	—	25,600,000 GBP	– GBP	—	– GBP	—	—	– GBP	—	– GBP	—	—	25,600,000 GBP	—	—	– GBP	– GBP	—	229,400,000 GBP	—	– GBP	—	—	– GBP	– GBP	229,400,000 GBP	—	—	—	—	—	—	—	—
Other comprehensive income	12,100,000 GBP	—	800,000 GBP	– GBP	—	– GBP	—	—	– GBP	—	– GBP	—	—	12,900,000 GBP	—	—	35,400,000 GBP	– GBP	—	4,300,000 GBP	—	– GBP	—	—	– GBP	– GBP	39,700,000 GBP	—	—	—	—	—	—	—	—
Comprehensive income	12,100,000 GBP	—	24,800,000 GBP	– GBP	—	– GBP	—	—	– GBP	—	– GBP	—	—	12,700,000 GBP	—	—	35,400,000 GBP	– GBP	—	233,700,000 GBP	—	– GBP	—	—	– GBP	– GBP	269,100,000 GBP	—	—	—	—	—	—	—	—
Dividends recognised as distributions to owners	– GBP	—	45,700,000 GBP	– GBP	—	– GBP	—	—	– GBP	—	– GBP	—	—	45,700,000 GBP	—	—	– GBP	– GBP	—	40,000,000 GBP	—	– GBP	—	—	– GBP	– GBP	40,000,000 GBP	—	—	—	—	—	—	—	—
Increase (decrease) through share-based payment transactions, equity	– GBP	—	2,400,000 GBP	– GBP	—	– GBP	—	—	– GBP	—	– GBP	—	—	2,400,000 GBP	—	—	– GBP	– GBP	—	1,700,000 GBP	—	– GBP	—	—	– GBP	– GBP	1,700,000 GBP	—	—	—	—	—	—	—	—