Note 7 - Related Party Transactions - Non-voting Revenues Interest and Non-voting Profits Interests (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2020	Oct. 31, 2019
Value Line’s non-voting revenues interest	$ 3,729	$ 2,768	$ 7,009	$ 5,356
Non-voting profits interest in EAM	485	290	849	573
Revenues and Profits Distribution from Unconsolidated Entity	$ 4,214	$ 3,058	$ 7,858	$ 5,929