Summary of significant accounting policies - Narrative (Details) $ in Millions	Jul. 31, 2025 USD ($) extension	Jul. 31, 2024 USD ($)
Accounting Policies [Line Items]
Rebates receivable | $	$ 471	$ 491
Supplier Finance Program, Obligation, Current, Statement of Financial Position [Extensible Enumeration]	Accounts payable	Accounts payable
Minimum
Accounting Policies [Line Items]
Lease term (in years)	3 years
Lease term, extension (in years)	2 years
Maximum
Accounting Policies [Line Items]
Lease term (in years)	10 years
Number of extension periods | extension	4
Lease term, extension (in years)	5 years