Pension and Other Postretirement Benefits (Funded Status Recorded on Accompanying Balance Sheets) (Details) - USD ($) $ in Millions	Apr. 30, 2023	Apr. 30, 2022
Funded status is recorded on the accompanying consolidated balance sheets
Accrued pension and other postretirement benefits	$ (171)	$ (183)
Pension Benefits [Member]
Funded status is recorded on the accompanying consolidated balance sheets
Other assets	17	46
Accounts payable and accrued expenses	(8)	(8)
Accrued pension and other postretirement benefits	(134)	(143)
Net liability	(125)	(105)
Accumulated other comprehensive income (loss), before tax:
Net actuarial gain (loss)	(192)	(201)
Prior service credit (cost)	(4)	(4)
Total	(196)	(205)
Medical and Life Insurance Benefits [Member]
Funded status is recorded on the accompanying consolidated balance sheets
Other assets	0	0
Accounts payable and accrued expenses	(3)	(3)
Accrued pension and other postretirement benefits	(37)	(40)
Net liability	(40)	(43)
Accumulated other comprehensive income (loss), before tax:
Net actuarial gain (loss)	(1)	(3)
Prior service credit (cost)	2	2
Total	$ 1	$ (1)