Note 4 - Investments - Assets and Liabilities (Details) - EAM Trust [Member] - USD ($) $ in Thousands		Apr. 30, 2018	Apr. 30, 2017
EAM's total assets		$ 60,203	$ 60,432
EAM's total liabilities (1)	[1]	(3,128)	(2,931)
EAM's total equity		$ 57,075	$ 57,501

[1] At October 31, 2017 and April 30, 2017, EAM's total liabilities included a payable to VLI for its accrued non-voting revenues interest and the 90% distributable share of its non-voting profits interest of $2,218,000 and $1,919,000, respectively.