Note 7 - Federal, State and Local Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Apr. 30, 2019	Apr. 30, 2018
Deferred tax liability	$ 12,624	$ 11,714
Deferred tax liability	12,624	11,714
Domestic Tax Authority [Member]
Deferred gain on deconsolidation of EAM	10,669	10,658
Deferred non-cash post-employment compensation	(372)	(372)
Depreciation and amortization	130	119
Unrealized gain on securities held for sale	446	208
Deferred charges	(354)	(331)
Other, asset	(279)	210
Deferred tax liability	10,240	10,492
Deferred tax liability	10,240	10,492
State and Local Jurisdiction [Member]
Deferred gain on deconsolidation of EAM	2,530	1,299
Deferred non-cash post-employment compensation	(74)	(45)
Depreciation and amortization	40	15
Deferred tax liability	2,384	1,222
Other	112	47
Deferred tax liability	$ 2,384	$ 1,222