Fair value measurements - Other Financial Instruments (Details) - USD ($) $ in Millions	24 Months Ended
	Jul. 31, 2025	Jul. 31, 2024
Fair value measurements
Fair value assets, transfer from level 1 to level 2	$ 0.0
Fair value assets, transfer from level 2 to level 1	0.0
Fair value liabilities, transfer from level 1 to level 2	0.0
Fair value liabilities, transfer from level 2 to level 1	0.0
Fair value assets, transfer into and out of level 3	0.0
Fair value liabilities, transfer into and out of level 3	0.0
Level 2
Fair value measurements
Long-term debt, fair value	$ 1,404.9	$ 1,416.8