Note 6 - Comprehensive Income - Components of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Jan. 31, 2024	Oct. 31, 2023	Jul. 31, 2023	Jan. 31, 2023	Oct. 31, 2022	Jul. 31, 2022	Jan. 31, 2024	Jan. 31, 2023
Change in unrealized gains/(losses) on available-for-sale fixed income securities							$ (508)	$ 158
Change in unrealized gains/(losses) on available-for-sale fixed income securities							106	(33)
Change in unrealized gains/(losses) on available-for-sale fixed income securities							(402)	125
Other Comprehensive Income (Loss), Available-for-Sale Securities Adjustment, before Tax, Portion Attributable to Parent							(508)	158
Other comprehensive income (loss), available-for-sale securities, tax expense							106	(33)
Other Comprehensive Income (Loss), Available-for-Sale Securities Adjustment, Net of Tax, Portion Attributable to Parent	$ 258	$ (448)	$ (212)	$ 123	$ (3)	$ 5	$ (402)	$ 125

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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