Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	Apr. 30, 2021	Apr. 30, 2020
Tax Credit Carryforward [Line Items]
Valuation allowance	$ 4,914	$ 4,415
State [Member]
Tax Credit Carryforward [Line Items]
Gross amount of state tax credit carryforwards	3,800	3,900
Net deferred tax assets related to tax credit carryforwards	500	600
State [Member] | Other Liabilities [Member]
Tax Credit Carryforward [Line Items]
Net deferred tax assets related to tax credit carryforwards	500	800
Foreign Tax Authority [Member]
Tax Credit Carryforward [Line Items]
Valuation allowance	500
Gross amount of state tax credit carryforwards	$ 1,700	$ 1,200