Statement Of Changes In Equity [Abstract]

Grainger PLC - Filing #1958620

Concept	2022-10-01 to 2023-09-30	2022-10-01 to 2023-09-30	2022-10-01 to 2023-09-30	2022-10-01 to 2023-09-30	2022-10-01 to 2023-09-30	2022-10-01 to 2023-09-30	2022-10-01 to 2023-09-30	2021-10-01 to 2022-09-30	2021-10-01 to 2022-09-30	2021-10-01 to 2022-09-30	2021-10-01 to 2022-09-30	2021-10-01 to 2022-09-30	2021-10-01 to 2022-09-30	2021-10-01 to 2022-09-30
Statement of changes in equity [abstract]
Statement of changes in equity [line items]
Increase (decrease) through transactions with owners, equity	100,000 GBP	– GBP	200,000 GBP	– GBP	50,900,000 GBP	51,200,000 GBP	– GBP	41,300,000 GBP	300,000 GBP	– GBP	– GBP	– GBP	– GBP	41,600,000 GBP
Purchase of treasury shares	– GBP	– GBP	– GBP	– GBP	7,900,000 GBP	7,900,000 GBP	– GBP	3,300,000 GBP	– GBP	– GBP	– GBP	– GBP	– GBP	3,300,000 GBP