Note 11 - Comprehensive Income - Components of Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
Apr. 30, 2024	Apr. 30, 2023	Apr. 30, 2022
Change in unrealized gains on available-for-sale fixed income securities	$ (793)	$ 503	$ (34)
Change in unrealized gains on available-for-sale fixed income securities	166	(105)	7
Change in unrealized gains on available-for-sale fixed income securities	(627)	398	(27)
Other Comprehensive Income (Loss), Available-for-Sale Securities Adjustment, before Tax, Portion Attributable to Parent	(793)	503	(34)
Other comprehensive income (loss), available-for-sale securities, tax expense	166	(105)	7
Other Comprehensive Income (Loss), Available-for-Sale Securities Adjustment, Net of Tax, Portion Attributable to Parent	$ (627)	$ 398	$ (27)

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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