Pensions and Other Postretirement Benefits (Details 3) - USD ($) $ in Millions		12 Months Ended
		Apr. 30, 2024	Apr. 30, 2023	Apr. 30, 2022
Change in plan assets:
Company contributions		$ 4.1	$ 74.1	$ 5.3
Defined benefit pensions		(54.1)	(62.1)
Other postretirement benefits		(44.3)	(49.1)
Defined Benefit Pension Plans
Change in benefit obligation:
Benefit obligation at beginning of year		379.7	429.4
Service cost		0.9	1.2	1.7
Interest cost		18.5	17.8	12.4
Actuarial loss (gain) (A)	[1]	(18.4)	(14.9)
Benefits paid		(34.5)	(17.7)
Curtailment		(3.4)	0.0
Settlement		3.1	(36.1)
Foreign currency translation adjustments		0.0	0.0
Benefit obligation at end of year		345.9	379.7	429.4
Change in plan assets:
Fair value of plan assets at beginning of year		325.9	317.1
Actual return on plan assets		(12.3)	(11.1)
Company contributions		4.1	74.1
Benefits paid		(34.5)	(17.7)
Settlement		(0.1)	(36.1)
Foreign currency translation adjustments		(0.1)	(0.4)
Fair value of plan assets at end of year		283.0	325.9	317.1
Funded status of the plans		(62.9)	(53.8)
Defined benefit pensions		(54.1)	(62.1)
Other noncurrent assets		8.8	12.3
Accrued compensation		(17.6)	(4.0)
Other postretirement benefits		0.0	0.0
Net benefit liability		(62.9)	(53.8)
Other Postretirement Benefits
Change in benefit obligation:
Benefit obligation at beginning of year		54.7	59.7
Service cost		0.8	1.0	1.2
Interest cost		2.6	2.3	1.3
Actuarial loss (gain) (A)	[1]	(5.4)	(3.8)
Benefits paid		(3.8)	(4.3)
Curtailment		0.0	0.0
Settlement		0.0	0.0
Foreign currency translation adjustments		0.0	(0.2)
Benefit obligation at end of year		48.9	54.7	59.7
Change in plan assets:
Fair value of plan assets at beginning of year		0.0	0.0
Actual return on plan assets		0.0	0.0
Company contributions		3.8	4.3
Benefits paid		(3.8)	(4.3)
Settlement		0.0	0.0
Foreign currency translation adjustments		0.0	0.0
Fair value of plan assets at end of year		0.0	0.0	$ 0.0
Funded status of the plans		(48.9)	(54.7)
Defined benefit pensions		0.0	0.0
Other noncurrent assets		0.0	0.0
Accrued compensation		(4.6)	(5.6)
Other postretirement benefits		(44.3)	(49.1)
Net benefit liability		$ (48.9)	$ (54.7)

[1] The actuarial losses and gains for our defined benefit pension plans and other postretirement benefits were primarily due to changes in the discount rates used in determining the plan obligations.