Income Taxes (Schedule Of Significant Components Of Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Thousands	Apr. 30, 2017	Apr. 30, 2016
Deferred tax assets:
Pension benefits	$ 8,852	$ 24,930
Accounts receivable	6,938	5,981
Product liability	1,272	1,141
Employee benefits	7,914	7,101
Other	862	353
Gross deferred tax assets, before valuation allowance	29,921	44,373
Valuation allowance	(2,446)	(3,061)
Gross deferred tax assets, after valuation allowance	27,475	41,312
Deferred tax liabilities:
Inventory	297	440
Depreciation	9,131	8,298
Total	9,428	8,738
Net deferred tax asset	18,047	32,574
State [Member]
Deferred tax assets:
State tax credit carryforwards	$ 4,083	$ 4,867