Pension and Other Postretirement Benefits (Details) - Pension Benefits [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jan. 31, 2023	Jan. 31, 2022	Jan. 31, 2023	Jan. 31, 2022
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Sponsor Location [Extensible List]
Service cost	$ 5	$ 7	$ 16	$ 20
Interest cost	8	5	24	16
Expected return on plan assets	(11)	(11)	(33)	(34)
Amortization of prior service cost (credit)	0	0	1	1
Amortization of net actuarial loss (gain)	2	6	7	18
Settlement loss	27	0	27	1
Net cost	$ 31	$ 7	$ 42	$ 22