Note 7 - Related Party Transactions - Non-voting Revenues Interest and Non-voting Profits Interests (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2020	Jan. 31, 2019
Value Line’s non-voting revenues interest	$ 3,033	$ 1,997	$ 8,389	$ 6,060
Non-voting profits interest in EAM	422	213	995	805
	$ 3,455	$ 2,210	$ 9,384	$ 6,865