Investments - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
Apr. 30, 2023	Apr. 30, 2022	Apr. 30, 2021
Net Investment Income [Line Items]
Carrying value of investment	$ 23,900	$ 16,800
Marketable Equity Securities
Net Investment Income [Line Items]
Net unrealized holding gains (losses)	100	600	$ 3,500
Net realized holding gains (losses)	(100)	(200)	100
Portfolio Debt Securities
Net Investment Income [Line Items]
Net unrealized holding gains (losses)	0	24	74
Net realized holding gains (losses)	0	(38)	(100)
US Treasury Securities
Net Investment Income [Line Items]
Net unrealized holding gains (losses)	100	0	0
Net realized holding gains (losses)	$ 0	$ 0	$ 0

Sum of the carrying amounts as of the balance sheet date of all investments.

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