Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	Apr. 30, 2019	Apr. 30, 2018
Tax Credit Carryforward [Line Items]
Valuation allowance	$ 3,630	$ 2,467
State [Member]
Tax Credit Carryforward [Line Items]
Gross amount of state tax credit carryforwards	4,600	5,200
Net deferred tax assets related to tax credit carryforwards	800	1,500
State [Member] | Other Liabilities [Member]
Tax Credit Carryforward [Line Items]
Net deferred tax assets related to tax credit carryforwards	1,000	$ 1,300
Foreign Tax Authority [Member]
Tax Credit Carryforward [Line Items]
Valuation allowance	700
Gross amount of state tax credit carryforwards	700
Investment Tax Credit Carryforward [Member]
Tax Credit Carryforward [Line Items]
Valuation allowance	$ 500