Restructuring and impairment expenses - Schedule of Restructuring Expenses (Details) - USD ($)	12 Months Ended
	Jul. 31, 2025	Jul. 31, 2024	Jul. 31, 2023
Restructuring Cost and Reserve [Line Items]
Impairment expenses	$ 0	$ 0	$ 107,000,000
Restructuring expenses	80,000,000	28,000,000	125,000,000
Corporate restructuring expenses
Restructuring Cost and Reserve [Line Items]
Corporate and business restructuring expenses	7,000,000	28,000,000	0
Business restructuring expenses
Restructuring Cost and Reserve [Line Items]
Corporate and business restructuring expenses	$ 73,000,000	$ 0	$ 18,000,000