Pension and Other Postretirement Benefits (Schedule of Components of Pension Expense) (Details) - Pension Benefits [Member] - USD ($) $ in Millions	12 Months Ended
	Apr. 30, 2024	Apr. 30, 2023	Apr. 30, 2022
Pension Expense
Service cost	$ 18	$ 20	$ 26
Interest cost	34	32	22
Expected return on assets	(40)	(43)	(45)
Amortization of prior service cost (credit)	1	1	1
Amortization of net actuarial loss (gain)	6	9	23
Settlement charge	0	29	12
Net cost	$ 19	$ 48	$ 39