Note 7 - Related Party Transactions - Schedule of Non Voting Revenues Interest and Non Voting Profits Interests (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2017	Jan. 31, 2016
Value Line’s non-voting revenues interest	$ 1,803	$ 1,825	$ 5,389	$ 5,546
Non-voting profits interest in EAM	131	94	393	355
	$ 1,934	$ 1,919	$ 5,782	$ 5,901