Income Taxes (NOL and Tax Credit Valuation Allowances) (Details) - USD ($) $ in Millions	12 Months Ended
	Jul. 31, 2023	Jul. 31, 2022	Jul. 31, 2021
Valuation Allowance, Deferred Tax Asset
Balance as of beginning of year	$ (3.4)	$ (4.6)	$ (8.1)
Additions charged to costs and expenses	(3.0)	(0.9)	(0.8)
Deductions from reserves	0.0	2.1	4.3
Balance as of end of year	$ (6.4)	$ (3.4)	$ (4.6)