Leases (Details 3) - USD ($) $ in Millions	Jul. 31, 2020	Apr. 30, 2020
Operating Lease Liabilities, Payments Due [Abstract]
2021 (remainder of the year)	$ 30.2
2022	37.1
2023	34.4
2024	22.8
2025	14.8
2026 and beyond	20.1
Total undiscounted minimum lease payments	159.4
Less: Imputed interest	11.0
Total operating lease liabilities	148.4	$ 156.5
Finance Lease Liabilities, Payments, Due [Abstract]
2021 (remainder of the year)	1.8
2022	1.7
2023	1.0
2024	0.7
2025	0.3
2026 and beyond	0.1
Total undiscounted minimum lease payments	5.6
Less: Imputed interest	0.3
Total finance lease liabilities	$ 5.3	$ 5.7