Pension and Other Postretirement Benefits (Details) - Pension Benefits [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Oct. 31, 2022	Oct. 31, 2021	Oct. 31, 2022	Oct. 31, 2021
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Sponsor Location [Extensible List]
Service cost	$ 5	$ 6	$ 10	$ 13
Interest cost	8	6	16	11
Expected return on plan assets	(11)	(11)	(22)	(23)
Amortization of prior service cost (credit)	0	0	0	1
Amortization of net actuarial loss (gain)	3	6	5	12
Settlement loss	0	1	0	1
Net cost	$ 5	$ 8	$ 9	$ 15