Note 4 - Investments - Income From Securities Transactions (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2023	Apr. 30, 2022	Apr. 30, 2021
Dividend income	$ 595	$ 851	$ 573
Interest income	706	18	137
Investment gains/(losses) recognized on sales of equity securities during the period	(81)	(1,568)	835
Unrealized gains/(losses) recognized on equity securities held at the end of the period	(45)	167	3,875
Other	(1)	(2)	0
Total investment gains/(losses)	$ 1,174	$ (534)	$ 5,420