Note 8 - Federal, State and Local Income Taxes - Schedule of Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2017	Jan. 31, 2016
Current tax expense:
Federal	$ 851	$ 906	$ 5,424	$ 2,916
State and local	166	62	506	189
Current tax expense	1,017	968	5,930	3,105
Deferred tax expense (benefit):
Federal	(282)	(271)	(870)	(449)
State and local	(325)	(1)	(387)	(222)
Deferred tax expense (benefit):	(607)	(272)	(1,257)	(671)
Income tax provision	$ 409	$ 696	$ 4,673	$ 2,434