Note 6 - Comprehensive Income - Components of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Jan. 31, 2023	Oct. 31, 2022	Jul. 31, 2022	Jan. 31, 2022	Oct. 31, 2021	Jul. 31, 2021	Jan. 31, 2023	Jan. 31, 2022
Change in unrealized gains on available-for-sale fixed income securities							$ 158	$ (5)
Change in unrealized gains on available-for-sale fixed income securities							(33)	1
Change in unrealized gains on available-for-sale fixed income securities							125	(4)
Other Comprehensive Income (Loss), Available-for-Sale Securities Adjustment, before Tax, Portion Attributable to Parent, Total							158	(5)
Other comprehensive income (loss), available-for-sale securities, tax expense							(33)	1
Other Comprehensive Income (Loss), Available-for-Sale Securities Adjustment, Net of Tax, Portion Attributable to Parent, Total	$ 123	$ (3)	$ 5	$ 0	$ 0	$ (4)	$ 125	$ (4)

Amount before tax, after reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities, attributable to parent entity. Excludes amounts related to other than temporary impairment (OTTI) loss.

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