Share-Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Apr. 30, 2021	Apr. 30, 2020	Apr. 30, 2019
Number of Stock Options Outstanding
Balance at beginning of period (in shares)	32,877	23,372
Options granted (in shares)	14,504	16,619
Options exercised (in shares)	(5,799)	(1,809)
Options cancelled (in shares)	(3,095)	(5,305)
Balance at end of period (in shares)	38,487	32,877	23,372
Vested and exercisable at end of period (in shares)	13,290
Vested and expected to vest at end of period (in shares)	39,578
Weighted Average Exercise Price
Balance at beginning of period (in dollars per share)	$ 3.48	$ 2.46
Options granted (in dollars per share)	11.50	4.86
Options exercised (in dollars per share)	2.90	2.34
Options cancelled (in dollars per share)	5.89	3.84
Balance at end of period (in dollars per share)	6.39	$ 3.48	$ 2.46
Vested and exercisable at end of period (in dollars per share)	3.35
Vested and expected to vest at end of period (in dollars per share)	$ 6.35
Weighted Average Remaining Contractual Life (years)
Balance at beginning of period	7 years 11 months 23 days	8 years 10 days	7 years 11 months 23 days
Balance at end of period	7 years 11 months 23 days	8 years 10 days	7 years 11 months 23 days
Vested and exercisable at end of period	6 years 6 months 18 days
Vested and expected to vest at end of period	7 years 11 months 23 days
Aggregate Intrinsic Value
Balance at beginning of period	$ 2,304,714	$ 116,962	$ 50,679
Balance at end of period	2,304,714	$ 116,962	$ 50,679
Vested and exercisable at end of period	835,990
Vested and expected to vest at end of period	$ 2,371,708