Leases (Supplemental Information) (Details) - USD ($) $ in Millions	Apr. 30, 2020	Aug. 01, 2019	Jul. 31, 2019
Leases [Abstract]
Right-of-use lease assets	$ 71.4	$ 71.5	$ 0.0
Current lease liabilities	24.0	26.0	0.0
Long-term lease liabilities	$ 47.4	$ 45.5	$ 0.0
Weighted average remaining lease term (years)	5 years	3 years 8 months 12 days
Weighted average discount rates (percentage)	3.57%	3.76%