Marketable Securities - Summary of Fair Value of Company's Investments By Type (Detail) - USD ($) $ in Thousands	Apr. 30, 2022	Apr. 30, 2021
Marketable Securities [Line Items]
Amortized Cost	$ 136,599	$ 198,536
Unrealized Gains	2	62
Unrealized Losses	(1,131)	(261)
Fair Value	135,470	198,337
Corporate Debt Securities [Member]
Marketable Securities [Line Items]
Amortized Cost	112,997	158,063
Unrealized Gains	2	55
Unrealized Losses	(994)	(245)
Fair Value	112,005	157,873
Obligations of U.S. Government and Its Agencies [Member]
Marketable Securities [Line Items]
Amortized Cost	23,602	40,473
Unrealized Gains		7
Unrealized Losses	(137)	(16)
Fair Value	$ 23,465	$ 40,464

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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Amount, before tax, of unrealized loss 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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Amortized cost of 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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Amount of 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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