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, 2019	Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018
Value Line’s non-voting revenues interest	$ 2,768	$ 2,095	$ 5,356	$ 4,063
Non-voting profits interest in EAM	290	289	573	592
	$ 3,058	$ 2,384	$ 5,929	$ 4,655