Debt - Narrative (Details) - USD ($)	2 Months Ended	12 Months Ended
	Sep. 26, 2025	Jul. 31, 2025	Jul. 31, 2024	Jul. 31, 2023	Apr. 30, 2025	Oct. 31, 2024	Oct. 07, 2022	Nov. 30, 2017	Jun. 30, 2015
Schedule Of Long-Term And Short-Term Debt [Line Items]
Hedged liability, fair value hedge		$ 150,000,000	$ 300,000,000
Repayments of debt		4,400,000,000	2,110,000,000	$ 2,930,000,000
Principal amount of debt		4,175,000,000	3,950,000,000
Variable Rate, Receivable Securitization
Schedule Of Long-Term And Short-Term Debt [Line Items]
Accordion feature, maximum amount		$ 1,500,000,000
Credit spread adjustment		0.10%
Interest rate during period		5.25%
Private Placement Notes:
Schedule Of Long-Term And Short-Term Debt [Line Items]
Aggregate principal amount								$ 355,000,000	$ 800,000,000
Percentage of principal amount redeemed (in percent)		100.00%
Private Placement Notes: | Subsequent Event
Schedule Of Long-Term And Short-Term Debt [Line Items]
Repayments of debt	$ 400,000,000
Interest rate	3.73%
Unsecured Senior Notes:
Schedule Of Long-Term And Short-Term Debt [Line Items]
Aggregate principal amount		$ 3,100,000,000				$ 750,000,000
Redemption price (in percent)		100.00%
Unsecured Senior Notes: | Ferguson Finance PLC
Schedule Of Long-Term And Short-Term Debt [Line Items]
Aggregate principal amount		$ 2,350,000,000
Unsecured Senior Notes: | Subsequent Event | 2031 Senior Notes
Schedule Of Long-Term And Short-Term Debt [Line Items]
Aggregate principal amount	$ 750,000,000
Interest rate	4.35%
Line of Credit | Revolving Credit Facility
Schedule Of Long-Term And Short-Term Debt [Line Items]
Line of credit facility aggregate committed amount					$ 1,500,000,000
Line of credit facility, accordion feature, increase limit					$ 500,000,000
Line of credit facility							$ 1,350,000,000
Borrowings outstanding		0	0
Corporate | Variable Rate, Receivable Securitization
Schedule Of Long-Term And Short-Term Debt [Line Items]
Line of credit facility		915,000,000
Term Loan | Term Loan
Schedule Of Long-Term And Short-Term Debt [Line Items]
Principal amount of debt		$ 0	$ 500,000,000				$ 500,000,000