Federal, State and Local Income Taxes - Tax effect of temporary differences in deferred tax asset and deferred tax liability (Details 1) - USD ($) $ in Thousands	Jan. 31, 2016	Apr. 30, 2015
Deferred Tax Assets and Liabilities [Line Items]
Deferred tax asset, short term	$ 375	$ 356
Deferred tax liability, long term	21,528	22,064
Federal tax liability (benefit)
Deferred Tax Assets and Liabilities [Line Items]
Unrealized gains on securities available-for-sale	26	(57)
Operating lease deferred obligation	70	70
Deferred professional fees	76	34
Deferred charges	173	263
Deferred tax asset, short term	345	310
Deferred gain on deconsolidation of EAM	17,716	17,679
Deferred non-cash post-employment compensation	(619)	(619)
Depreciation and amortization	2,229	2,435
Other	332	401
Deferred tax liability, long term	19,658	19,896
State and local tax liabilities (benefits)
Deferred Tax Assets and Liabilities [Line Items]
Other	30	46
Deferred tax asset, short term	30	46
Deferred gain on deconsolidation of EAM	1,735	1,970
Deferred non-cash post-employment compensation	(61)	(69)
Depreciation and amortization	218	271
Other	(22)	(4)
Deferred tax liability, long term	$ 1,870	$ 2,168