Note 2 - Investments - Assets and Liabilities (Details) - USD ($) $ in Thousands		Oct. 31, 2023	Jul. 31, 2023	Apr. 30, 2023	Oct. 31, 2022	Jul. 31, 2022	Apr. 30, 2022
EAM's total assets		$ 130,341		$ 131,076
EAM's total liabilities		44,599		47,403
EAM's total equity		85,742	$ 85,491	83,673	$ 80,220	$ 79,357	$ 79,645
EAM Trust [Member]
EAM's total assets		61,729		61,389
EAM's total liabilities	[1]	4,763		4,357
EAM's total equity		$ 56,966		$ 57,032

[1] At July 31, 2023 and April 30, 2023, EAM's total liabilities included a payable to VLI for its accrued non-voting revenues interest and non-voting profits interest of $2,833,000 and $2,601,000, respectively.