Note 2 - Investments - Assets and Liabilities (Details) - USD ($) $ in Thousands		Oct. 31, 2020	Apr. 30, 2020	Oct. 31, 2019	Apr. 30, 2019
EAM's total assets		$ 110,837	$ 109,728
EAM's total liabilities (1)		51,609	56,189
EAM's total equity		59,228	53,539	$ 51,531	$ 47,524
EAM Trust [Member]
EAM's total assets		63,549	61,335
EAM's total liabilities (1)	[1]	6,529	4,192
EAM's total equity		$ 57,020	$ 57,143

[1] At October 31, 2020 and April 30, 2020, EAM's total liabilities included a payable to VLI for its accrued non-voting revenues interest and non-voting profits interest of $4,165,000 and $2,949,000, respectively.