Note 8 - Federal, State and Local Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2020	Oct. 31, 2019
Federal	$ 1,351	$ 1,143	$ 2,664	$ 2,133
State and local	344	319	697	615
Current tax expense	1,695	1,462	3,361	2,748
Federal	(20)	(38)	24	(54)
State and local	(6)	195	(5)	272
Deferred tax expense (benefit):	(26)	157	19	218
Income tax provision	$ 1,669	$ 1,619	$ 3,380	$ 2,966