Pension and Other Postretirement Benefits (Plans with ABO in Excess of Plan Assets) (Details) - USD ($) $ in Millions	Apr. 30, 2023	Apr. 30, 2022	Apr. 30, 2021
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total, Plan Assets	$ 606	$ 741
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Accumulated Benefit Obligation	(131)	(135)
Defined Benefit Plan Pension Plans With Assets In Excess Of Accumulated Benefit Obligation Aggregate Accumulated Benefit Obligation	(524)	(623)
Defined Benefit Plan, Accumulated Benefit Obligation	(655)	(758)
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Plan Assets	0	0
Defined Benefit Plan Pension Plans With Assets In Excess Of Accumulated Benefit Obligation Aggregate Fair Value Of Plan Assets	606	741
Total, Plan Assets	$ 606	$ 741	$ 836