Segment and net sales information - Identifiable Assets (Details) - USD ($) $ in Millions	Jul. 31, 2025	Jul. 31, 2024
Segment Reporting Information [Line Items]
Total assets	$ 17,729	$ 16,572
Total long-lived assets	1,846	1,752
United States
Segment Reporting Information [Line Items]
Total long-lived assets	1,795	1,699
Canada
Segment Reporting Information [Line Items]
Total long-lived assets	51	53
Operating Segments
Segment Reporting Information [Line Items]
Total assets	16,765	15,693
Corporate
Segment Reporting Information [Line Items]
Total assets	964	879
United States | Operating Segments
Segment Reporting Information [Line Items]
Total assets	15,757	14,795
Canada | Operating Segments
Segment Reporting Information [Line Items]
Total assets	$ 1,008	$ 898