Federal, State and Local Income Taxes - Tax effect of temporary differences in deferred tax asset and deferred tax liability (Details 1) (USD $)	Jul. 31, 2012	Apr. 30, 2012
Deferred Tax Assets and Liabilities [Line Items]
Total federal, state and local tax benefits	$ 221,000	$ 442,000
Deferred gain on deconsolidation of EAM	(50,510,000)
Deferred non-cash postemployment compensation	1,770,000
Deferred tax liability, long-term	20,772,000	20,424,000
Federal Tax Benefit (Liability)
Deferred Tax Assets and Liabilities [Line Items]
Net operating loss		126,000
Unrealized gains on securities held for sale	(61,000)	(46,000)
Operating lease exit obligation	128,000	153,000
Deferred professional fees		80,000
Deferred charges	135,000	76,000
Total federal, state and local tax benefits	202,000	389,000
Deferred gain on deconsolidation of EAM	17,679,000	17,679,000
Deferred non-cash postemployment compensation	(619,000)	(619,000)
Depreciation and amortization	1,418,000	1,032,000
Other	117,000	120,000
Deferred tax liability, long-term	18,595,000	18,212,000
State and Local Tax Liability (Benefit)
Deferred Tax Assets and Liabilities [Line Items]
Net operating loss		15,000
Other	19,000	38,000
Total federal, state and local tax benefits	19,000	53,000
Deferred gain on deconsolidation of EAM	2,087,000	2,182,000
Deferred non-cash postemployment compensation	(73,000)	(76,000)
Depreciation and amortization	168,000	127,000
Deferred professional fees	(5,000)	(21,000)
Deferred tax liability, long-term	$ 2,177,000	$ 2,212,000