Note 11 - Comprehensive Income - Components of Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
Apr. 30, 2023	Apr. 30, 2022	Apr. 30, 2021
Change in unrealized gains on available-for-sale fixed income securities	$ 503	$ (34)	$ (173)
Change in unrealized gains on available-for-sale fixed income securities	(105)	7	45
Change in unrealized gains on available-for-sale fixed income securities	398	(27)	(128)
Other Comprehensive Income (Loss), Available-for-Sale Securities Adjustment, before Tax, Portion Attributable to Parent	503	(34)	(173)
Other comprehensive income (loss), available-for-sale securities, tax expense	(105)	7	45
Other Comprehensive Income (Loss), Available-for-Sale Securities Adjustment, Net of Tax, Portion Attributable to Parent	$ 398	$ (27)	$ (128)

Amount, before tax and after reclassification adjustment, of gain (loss) in value of unsold investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), attributable to parent.

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