Note 5 - Variable Interest Entity - Total Assets, the Maximum Exposure to Loss, and Value of the Assets and Liabilities in EAM (Details) - USD ($)		Apr. 30, 2018	Apr. 30, 2017
Equity Method Investments		$ 58,233,000	$ 58,223,000
EAM Trust [Member]
VIE Assets		60,203,000	60,432,000
Equity Method Investments	[1]	58,233,000	58,223,000
Value Line Liabilities
Value Line Liabilities		$ 58,233,000	$ 58,223,000

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