Note 7 - Federal, State and Local Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Apr. 30, 2020	Apr. 30, 2019
Right of Use Asset	$ 182
Deferred tax liability	12,851	12,624
Domestic Tax Authority [Member]
Deferred gain on deconsolidation of EAM	10,669	10,669
Deferred non-cash post-employment compensation	(372)	(372)
Depreciation and amortization	108	130
Unrealized gain on securities held for sale	(299)	(446)
Deferred charges	(166)	(354)
Other	(207)	(279)
Deferred tax liability	10,149	10,240
State and Local Jurisdiction [Member]
Deferred gain on deconsolidation of EAM	2,564	2,530
Deferred non-cash post-employment compensation	(88)	(74)
Depreciation and amortization	44	40
Unrealized gain on securities held for sale	72	106
Other	110	(218)
Deferred tax liability	$ 2,702	$ 2,384