Note 2 - Investments - Income From Securities Transactions (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 31, 2021	Oct. 31, 2020	Oct. 31, 2021	Oct. 31, 2020
Dividend income	$ 210	$ 137	$ 406	$ 258
Interest income	0	44	1	100
Investment gains/(losses) recognized on sales of equity securities during the period	47	144	47	444
Unrealized gains/(losses) recognized on equity securities held at the end of the period	111	(187)	309	508
Other	0	0	(1)	(2)
Total investment gains	$ 368	$ 138	$ 762	$ 1,308