Leases (Details 1) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Oct. 31, 2021	Oct. 31, 2020	Oct. 31, 2021	Oct. 31, 2020
Leases [Abstract]
Operating lease cost	$ 10.6	$ 11.1	$ 21.4	$ 22.4
Finance lease cost:
Amortization of right-of-use assets	0.6	0.6	1.1	1.2
Interest on lease liabilities	0.1	0.0	0.1	0.1
Variable lease cost	5.7	5.5	11.0	11.1
Short-term lease cost	9.3	10.3	20.1	19.3
Sublease income	(0.3)	(1.0)	(0.6)	(2.5)
Net lease cost	$ 26.0	$ 26.5	$ 53.1	$ 51.6