Assets and liabilities at fair value -Debt Measured at Fair Value (Details) - Level 2 - USD ($) $ in Millions	Oct. 31, 2024	Jul. 31, 2024
Unsecured senior notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Amount	$ 3,078	$ 2,333
Fair Value	2,978	2,263
Private placement notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Amount	850	849
Fair Value	$ 843	$ 837