Note 2 - Investments - Components of EAM's Investment Management Operations (Details) - USD ($) $ in Thousands		3 Months Ended
		Jul. 31, 2018	Jul. 31, 2017
Revenues		$ 8,971	$ 8,914
Value Line’s non-voting revenues interest		1,968	1,978
EAM's net income (1)		3,104	2,215
EAM Trust [Member]
Other income		71	55
Investment management fee waivers		111	154
12b-1 fee waivers		159	235
Value Line’s non-voting revenues interest		1,968	1,978
EAM's net income (1)	[1]	606	316
EAM Trust [Member] | Investment Advice [Member]
Revenues		4,109	3,958
EAM Trust [Member] | Distribution and Shareholder Service [Member]
Revenues		$ 1,704	$ 1,549

[1] Represents EAM's net income, after giving effect to Value Line's non-voting revenues interest, but before distributions to voting profits interest holders and to the Company in respect of its 50% non-voting profits interest.