Investments - Available For Sale Securities (Details) - Available-for-sale securities. - USD ($) $ in Thousands	Apr. 30, 2022	Apr. 30, 2021
Available-For-Sale Securities
Amortized Cost	$ 24,751	$ 36,953
Gross Unrealized Gains		9
Gross Unrealized Losses	(35)	(3)
Total	24,716	36,959
Municipal securities
Available-For-Sale Securities
Amortized Cost	19,756	23,227
Gross Unrealized Gains		8
Gross Unrealized Losses	(31)	(2)
Total	19,725	23,233
U.S. government securities
Available-For-Sale Securities
Amortized Cost	4,995	8,008
Gross Unrealized Gains		1
Gross Unrealized Losses	(4)
Total	$ 4,991	8,009
Corporate bonds
Available-For-Sale Securities
Amortized Cost		5,718
Gross Unrealized Losses		(1)
Total		$ 5,717

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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