Note 8 - Federal, State and Local Income Taxes - Schedule of Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 31, 2016	Oct. 31, 2015	Oct. 31, 2016	Oct. 31, 2015
Current tax expense:
Federal	$ 996	$ 986	$ 4,573	$ 2,010
State and local	15	55	340	127
Current tax expense	1,011	1,041	4,913	2,137
Deferred tax expense (benefit):
Federal	(399)	(166)	(588)	(178)
State and local	(77)	(70)	(62)	(221)
Deferred tax expense (benefit):	(476)	(236)	(650)	(399)
Income tax provision	$ 535	$ 805	$ 4,263	$ 1,738