Other Income - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2022	Apr. 30, 2021	Apr. 30, 2020
Research and development tax credit receivable	$ 14,098	$ 10,418
Other Income [Member]
Realized (loss) gains from sale of available for sale securities	(600)	200	$ 300
R&D Credit Carryforward [Member]
Revenue recognized	$ 15,300	$ 9,800	$ 9,500