Pension and Other Postretirement Benefits (Details) - Pension Benefits [Member] - USD ($) $ in Millions	3 Months Ended
	Jul. 31, 2022	Jul. 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	$ 7
Interest cost	8	5
Expected return on plan assets	(11)	(11)
Amortization of net actuarial loss (gain)	3	6
Net cost	$ 5	$ 7