Income tax - Schedule of Unrecognized Tax Benefits Roll Forward (Details) - USD ($) $ in Millions	12 Months Ended
	Jul. 31, 2025	Jul. 31, 2024	Jul. 31, 2023
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits at beginning of fiscal year	$ 151	$ 144	$ 140
Additions based on tax positions related to current year	5	25	27
Additions for tax positions of prior years	2	2	2
Reductions for tax positions of prior years	0	(10)	0
Reductions due to lapse of statute of limitations	(32)	(10)	(25)
Unrecognized tax benefits	$ 126	$ 151	$ 144