Share-based compensation - Narrative (Details) $ / shares in Units, $ in Millions	6 Months Ended
Jun. 30, 2026 USD ($) $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share based payment, cost not yet recognized \| $	$ 141
Share based payment, cost not yet recognized, period for recognition (in years)	2 years 1 month 6 days
Ferguson Group Employee Share Purchase Plan 2021
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Remain available for allotment under the ESPP (in shares)	20,000,000
RSU awards granted
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share based compensation, award vesting period (in years)	3 years
PSU-EX granted
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share based compensation, award vesting period (in years)	3 years
Stock Option
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share based compensation, award vesting period (in years)	3 years
Service period	1 year
Expiration period	10 years
Employee Stock \| Ferguson Group Employee Share Purchase Plan 2021
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Remain available for allotment under the ESPP (in shares)	19,500,000
Offering period	85.00%
Shares purchased under the ESPP (in shares)	136,659
Average price (in usd per share) \| $ / shares	$ 132.23

Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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Per share weighted-average price paid for shares purchased on open market for issuance under share-based payment arrangement.

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Number of shares issued under share-based payment arrangement.

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Period from grant to expiration date of share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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