Pensions and Other Postretirement Benefits (Details 3) - USD ($) $ in Millions		12 Months Ended
		Apr. 30, 2023	Apr. 30, 2022	Apr. 30, 2021
Change in plan assets:
Company contributions		$ 74.1	$ 5.3	$ 13.1
Defined benefit pensions		(62.1)	(114.9)
Other postretirement benefits		(49.1)	(54.2)
Defined Benefit Pension Plans
Change in benefit obligation:
Benefit obligation at beginning of year		429.4	546.8
Service cost		1.2	1.7	1.8
Interest cost		17.8	12.4	14.4
Amendments		0.0	0.4
Actuarial loss (gain) (A)	[1]	(14.9)	(62.4)
Benefits paid		(17.7)	(25.4)
Settlement		(36.1)	(44.1)
Foreign currency translation adjustments		0.0	0.0
Benefit obligation at end of year		379.7	429.4	546.8
Change in plan assets:
Fair value of plan assets at beginning of year		317.1	397.8
Actual return on plan assets		(11.1)	(16.1)
Company contributions		74.1	5.3
Benefits paid		(17.7)	(25.4)
Settlement		(36.1)	(44.1)
Foreign currency translation adjustments		(0.4)	(0.4)
Fair value of plan assets at end of year		325.9	317.1	397.8
Funded status of the plans		(53.8)	(112.3)
Defined benefit pensions		(62.1)	(114.9)
Other noncurrent assets		12.3	6.6
Liability, Defined Benefit Plan, Current		(4.0)	(4.0)
Other postretirement benefits		0.0	0.0
Net benefit liability		(53.8)	(112.3)
Other Postretirement Benefits
Change in benefit obligation:
Benefit obligation at beginning of year		59.7	69.6
Service cost		1.0	1.2	1.8
Interest cost		2.3	1.3	1.8
Amendments		0.0	0.0
Actuarial loss (gain) (A)	[1]	(3.8)	(8.2)
Benefits paid		(4.3)	(4.1)
Settlement		0.0	0.0
Foreign currency translation adjustments		(0.2)	(0.1)
Benefit obligation at end of year		54.7	59.7	69.6
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		4.3	4.1
Benefits paid		(4.3)	(4.1)
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		(54.7)	(59.7)
Defined benefit pensions		0.0	0.0
Other noncurrent assets		0.0	0.0
Liability, Defined Benefit Plan, Current		(5.6)	(5.5)
Other postretirement benefits		(49.1)	(54.2)
Net benefit liability		$ (54.7)	$ (59.7)

[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.