Revenue and segment information - Disaggregation of Net Sales (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 31, 2025	Jan. 31, 2024	Jan. 31, 2025	Jan. 31, 2024
Segment Reporting Information [Line Items]
Total net sales	$ 6,872	$ 6,673	$ 14,644	$ 14,381
United States
Segment Reporting Information [Line Items]
Total net sales	6,553	6,364	13,922	13,693
Canada
Segment Reporting Information [Line Items]
Total net sales	319	309	722	688
Residential | United States
Segment Reporting Information [Line Items]
Total net sales	3,371	3,299	7,118	7,039
Non-residential: | United States
Segment Reporting Information [Line Items]
Total net sales	3,182	3,065	6,804	6,654
Commercial | United States
Segment Reporting Information [Line Items]
Total net sales	2,188	2,122	4,653	4,592
Civil/Infrastructure | United States
Segment Reporting Information [Line Items]
Total net sales	555	508	1,205	1,141
Industrial | United States
Segment Reporting Information [Line Items]
Total net sales	$ 439	$ 435	$ 946	$ 921