Note 8 - Federal, State and Local Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2021	Jan. 31, 2020
Federal	$ 1,525	$ 1,347	$ 4,189	$ 3,480
State and local	108	300	805	915
Current tax expense	1,633	1,647	4,994	4,395
Federal	153	154	177	100
State and local	(374)	(2)	(379)	270
Deferred tax expense (benefit):	(221)	152	(202)	370
Income tax provision	$ 1,412	$ 1,799	$ 4,792	$ 4,765