Revenue and segment information - Disaggregation of Net Sales (Details) - USD ($) $ in Millions	3 Months Ended
	Oct. 31, 2024	Oct. 31, 2023
Segment Reporting Information [Line Items]
Total net sales	$ 7,772	$ 7,708
United States
Segment Reporting Information [Line Items]
Total net sales	7,369	7,329
Canada
Segment Reporting Information [Line Items]
Total net sales	403	379
Residential | United States
Segment Reporting Information [Line Items]
Total net sales	3,747	3,740
Non-residential: | United States
Segment Reporting Information [Line Items]
Total net sales	3,622	3,589
Commercial | United States
Segment Reporting Information [Line Items]
Total net sales	2,465	2,470
Civil/Infrastructure | United States
Segment Reporting Information [Line Items]
Total net sales	650	633
Industrial | United States
Segment Reporting Information [Line Items]
Total net sales	$ 507	$ 486