Note 3 - Variable Interest Entity - Total Assets, the Maximum Exposure to Loss, and Value of the Assets and Liabilities in EAM (Details) - USD ($)		Jul. 31, 2018	Apr. 30, 2018
Equity Method Investments		$ 58,331,000	$ 58,233,000
EAM Trust [Member]
VIE Assets		60,278,000	60,203,000
Equity Method Investments	[1]	58,331,000	58,233,000
Value Line Liabilities
Value Line Liabilities		$ 58,331,000	$ 58,233,000

[1] Reported within Long Term Assets on the Consolidated Condensed Balance Sheets.