Pension and Other Postretirement Benefits (Assumptions and SensItivity) (Details)	12 Months Ended
	Apr. 30, 2023	Apr. 30, 2022	Apr. 30, 2021
Pension Benefits [Member]
Assumptions used in computing benefit plan obligations
Discount rate (percent)	4.91%	4.36%
Rate of salary increase (percent)	4.00%	4.00%
Interest crediting rate (percent)	3.69%	3.06%
Assumptions used in computing benefit plan expense
Discount rate for service cost (percent)	4.52%	3.36%	3.49%
Discount rate for interest cost (percent)	4.12%	2.34%	2.56%
Rate of salary increase (percent)	4.00%	4.00%	4.00%
Interest crediting rate (percent)	3.06%	3.06%	3.07%
Expected return on plan assets (percent)	6.25%	6.25%	6.50%
Medical and Life Insurance Benefits [Member]
Assumptions used in computing benefit plan obligations
Discount rate (percent)	4.86%	4.33%
Assumptions used in computing benefit plan expense
Discount rate for service cost (percent)	4.50%	3.49%	3.59%
Discount rate for interest cost (percent)	3.96%	2.27%	2.47%
Assumed health care cost trend rates
Health care cost trend rate assumed for next year (percent)	7.23%	6.10%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate) (percent)	4.50%	4.50%