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, 2018	Jan. 31, 2017	Jan. 31, 2018	Jan. 31, 2017
Value Line’s non-voting revenues interest	$ 2,057	$ 1,803	$ 6,074	$ 5,389
Non-voting profits interest in EAM	227	131	583	393
	$ 2,284	$ 1,934	$ 6,657	$ 5,782