Income Taxes (Schedule Of Significant Components Of Deferred Tax Assets And Liabilities)(Details) (USD $) In Thousands, unless otherwise specified	Apr. 30, 2013	Apr. 30, 2012
Income Taxes [Abstract]
Deferred tax assets. Pension benefits	$ 20,563	$ 18,238
Deferred tax assets, Accounts receivable	3,983	3,103
Deferred tax assets, Product liability	700	735
Deferred tax assets, Employee benefits	11,243	10,878
Deferred tax assets, Net operating loss carryforward	1,099	6,686
Deferred tax assets, Income tax credits	1,088	747
Deferred tax assets. Depreciation	73	896
Deferred Tax Assets, Other	496	772
Total	39,245	42,055
Deferred tax liabilities, Inventory	502	0
Net deferred tax asset	$ 38,743	$ 42,055