Note 4 - Supplementary Cash Flows Information - Supplementary Cash Flow Elements (Details) - USD ($) $ in Thousands	6 Months Ended
	Oct. 31, 2023	Oct. 31, 2022	Apr. 30, 2023	Apr. 30, 2022
Cash and cash equivalents	$ 3,924	$ 12,668	$ 7,590
Restricted cash	305	305
Total cash, cash equivalents, and restricted cash shown in the Consolidated Condensed Statement of Cash Flows	4,229	12,973	$ 7,895	$ 30,008
State and local income tax payments	497	650
Federal income tax payments	$ 2,900	$ 3,127