Accumulated other comprehensive loss - Change in AOCI (Details) - USD ($) $ in Millions	3 Months Ended
	Oct. 31, 2024	Oct. 31, 2023
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 5,616
Other comprehensive (loss) income before reclassifications	(5)	$ (37)
Amounts reclassified from accumulated other comprehensive loss	3	3
Total other comprehensive loss, net of tax	(2)	(34)
Ending balance	5,655	5,360
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(931)	(888)
Total other comprehensive loss, net of tax	(2)	(34)
Ending balance	(933)	(922)
Foreign currency translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(461)	(429)
Other comprehensive (loss) income before reclassifications	(7)	(35)
Amounts reclassified from accumulated other comprehensive loss	0	0
Total other comprehensive loss, net of tax	(7)	(35)
Ending balance	(468)	(464)
Pensions
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(470)	(459)
Other comprehensive (loss) income before reclassifications	2	(2)
Amounts reclassified from accumulated other comprehensive loss	3	3
Total other comprehensive loss, net of tax	5	1
Ending balance	$ (465)	$ (458)