Net Loss Per Share Attributable to Ordinary Shareholders - Schedule of Computation of Basic and Diluted Net Loss Per Share Attributable to Ordinary Shareholders (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2018
Numerator:
Net loss	$ (167,174)	$ (102,303)	$ (52,727)
Denominator:
Weighted-average shares used to compute net loss per share attributable to ordinary shareholders, basic and diluted (in shares)	78,799,732	54,893,365	32,033,792
Net loss per share attributable to ordinary shareholders, basic and diluted (in dollars per share)	$ (2.12)	$ (1.86)	$ (1.65)