CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2021	Apr. 30, 2020	Apr. 30, 2019
Statement of Comprehensive Income [Abstract]
Net loss	$ (55,696)	$ (69,378)	$ (33,346)
Other comprehensive (loss) income
Unrealized (loss) gain on investment securities, net of tax	(343)	350	75
Total comprehensive loss	$ (56,039)	$ (69,028)	$ (33,271)