Note 7 - Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2021	Apr. 30, 2020
Current Income Tax Expense (Benefit), Total	$ 536	$ 1,594
Current Federal Tax Expense (Benefit)	328	1,151
Current State and Local Tax Expense (Benefit)	208	$ 443
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued, Total	$ 0