Leases (Details 3) - USD ($) $ in Millions	Oct. 31, 2020	Apr. 30, 2020
Operating Lease Liabilities, Payments Due [Abstract]
2021 (remainder of the year)	$ 20.2
2022	37.2
2023	34.6
2024	22.9
2025	15.0
2026 and beyond	20.7
Total undiscounted minimum lease payments	150.6
Less: Imputed interest	9.4
Total operating lease liabilities	141.2	$ 156.5
Finance Lease Liabilities, Payments, Due [Abstract]
2021 (remainder of the year)	1.2
2022	1.7
2023	1.1
2024	0.8
2025	0.3
2026 and beyond	0.1
Total undiscounted minimum lease payments	5.2
Less: Imputed interest	0.2
Total finance lease liabilities	$ 5.0	$ 5.7