Investments - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2018
Net Investment Income [Line Items]
Carrying value of investment	$ 14,900	$ 27,200
Investments-noncurrent	701	2,484
Marketable equity securities
Net Investment Income [Line Items]
Net unrealized holding gains (losses)	700	(900)	$ (1,000)
Net realized holding gains (losses)	(200)	(100)	0
Portfolio debt securities
Net Investment Income [Line Items]
Net unrealized holding gains (losses)	(600)	(100)	100
Net realized holding gains (losses)	$ 700	$ 700	$ 700

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

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The total amount of investments that are intended to be held for an extended period of time (longer than one operating cycle).

+ References

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The net realized gains or losses on investments during the period, not including gains or losses on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity.

+ References

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of investments, not including unrealized gains or losses on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity, held at each balance sheet date and included in earnings for the period.

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