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, 2019	Jan. 31, 2018	Jan. 31, 2019	Jan. 31, 2018
Value Line’s non-voting revenues interest	$ 1,997	$ 2,057	$ 6,060	$ 6,074
Non-voting profits interest in EAM	213	227	805	583
	$ 2,210	$ 2,284	$ 6,865	$ 6,657