Note 2 - Investments - Assets and Liabilities (Details) - EAM Trust [Member] - USD ($) $ in Thousands		Jan. 31, 2020	Apr. 30, 2019
EAM's total assets		$ 62,371	$ 60,683
EAM's total liabilities (1)	[1]	(5,293)	(3,547)
EAM's total equity		$ 57,078	$ 57,136

[1] At January 31, 2020 and April 30, 2019, EAM's total liabilities included a payable to VLI for its accrued non-voting revenues interest and non-voting profits interest of $3,413,000 and $2,420,000, respectively.