Note 7 - Related Party Transactions - Non-voting Revenues Interest and Non-voting Profits Interests (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		9 Months Ended
	Jan. 31, 2022	Jan. 31, 2021	Jan. 31, 2022	Jan. 31, 2021	Jan. 31, 2022	Jan. 31, 2021
Value Line’s non-voting revenues interest	$ 4,120	$ 4,104	$ 12,532	$ 11,113	$ 12,532	$ 11,113
Non-voting profits interest in EAM	535	630	$ 1,820	$ 1,479	1,820	1,479
Revenues and Profits Distribution from Unconsolidated Entity	$ 4,655	$ 4,734			$ 14,352	$ 12,592