Note 2 - Investments - Components of EAM's Investment Management Operations (Details) - USD ($) $ in Thousands		3 Months Ended
		Jul. 31, 2020	Jul. 31, 2019
Revenues		$ 10,328	$ 9,617
Value Line’s non-voting revenues interest		3,280	2,588
Net Income (Loss) Attributable to Parent, Total		5,117	3,690
EAM Trust [Member]
Other income		110	53
Investment management fee waivers and reimbursements		43	109
12b-1 fee waivers		157	173
Value Line’s non-voting revenues interest		3,280	2,588
Net Income (Loss) Attributable to Parent, Total	[1]	728	566
EAM Trust [Member] | Investment Advice [Member]
Revenues		6,310	5,147
EAM Trust [Member] | Distribution and Shareholder Service [Member]
Revenues		$ 2,301	$ 1,979

[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.