Note 6 - Comprehensive Income - Components of Comprehensive Income (Details) - USD ($)	3 Months Ended	6 Months Ended
Oct. 31, 2023	Jul. 31, 2023	Oct. 31, 2022	Jul. 31, 2022	Oct. 31, 2023	Oct. 31, 2022
Change in unrealized gains/(losses) on available-for-sale fixed income securities					$ (837,000)	$ 3,000
Change in unrealized gains/(losses) on available-for-sale fixed income securities					177,000	(1,000)
Change in unrealized gains/(losses) on available-for-sale fixed income securities					(660,000)	2,000
Other Comprehensive Income (Loss), Available-for-Sale Securities Adjustment, before Tax, Portion Attributable to Parent					(837,000)	3,000
Other comprehensive income (loss), available-for-sale securities, tax expense					177,000	(1,000)
Other Comprehensive Income (Loss), Available-for-Sale Securities Adjustment, Net of Tax, Portion Attributable to Parent	$ (448,000)	$ (212,000)	$ (3,000)	$ 5,000	$ (660,000)	$ 2,000

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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