Accumulated other comprehensive loss - Change in AOCI (Details) - USD ($) $ in Millions	12 Months Ended
	Jul. 31, 2024	Jul. 31, 2023	Jul. 31, 2022
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 5,037	$ 4,665	$ 5,003
Other comprehensive loss before reclassifications	(54)	(66)	(42)
Amounts reclassified from accumulated other comprehensive loss	11	8	8
Total other comprehensive loss, net of tax	(43)	(58)	(34)
Ending balance	5,616	5,037	4,665
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(888)	(830)	(796)
Total other comprehensive loss, net of tax	(43)	(58)	(34)
Ending balance	(931)	(888)	(830)
Foreign currency translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(429)	(420)	(396)
Other comprehensive loss before reclassifications	(32)	(9)	(24)
Amounts reclassified from accumulated other comprehensive loss	0	0	0
Total other comprehensive loss, net of tax	(32)	(9)	(24)
Ending balance	(461)	(429)	(420)
Pensions
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(459)	(410)	(400)
Other comprehensive loss before reclassifications	(22)	(57)	(18)
Amounts reclassified from accumulated other comprehensive loss	11	8	8
Total other comprehensive loss, net of tax	(11)	(49)	(10)
Ending balance	$ (470)	$ (459)	$ (410)