Marketable Securities - Summary of Scheduled Maturity for Investments (Detail) - USD ($) $ in Thousands	Apr. 30, 2020	Apr. 30, 2019
Investments Debt And Equity Securities [Abstract]
Maturing in one year or less	$ 32,391
Maturing after one year through two years	11,698
Maturing after two years	7,836
Total investments	$ 51,925	$ 68,805

Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), maturing in next fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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Balance Type:	debit
Period Type:	instant