Note 2 - Investments - Assets and Liabilities (Details) - USD ($) $ in Thousands		Jan. 31, 2024	Oct. 31, 2023	Jul. 31, 2023	Apr. 30, 2023	Jan. 31, 2023	Oct. 31, 2022	Jul. 31, 2022	Apr. 30, 2022
EAM's total assets		$ 134,541			$ 131,076
EAM's total liabilities		45,295			47,403
EAM's total equity		89,246	$ 85,742	$ 85,491	83,673	$ 82,226	$ 80,220	$ 79,357	$ 79,645
EAM Trust [Member]
EAM's total assets		62,610			61,389
EAM's total liabilities	[1]	5,532			4,357
EAM's total equity		$ 57,078			$ 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.