Equity Incentive Plans - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2018
Options, Outstanding Number [Roll Forward]
Stock options granted (in shares)	172,031	4,722,404
Stock options assumed in acquisition (in shares)	245,390
Stock options assumed in acquisition cancelled (in shares)	(26,773)
Options Outstanding, Weighted Average Exercise Price [Abstract]
Stock options assumed in acquisition (in dollars per share)	$ 48.99
Stock options assumed in acquisition cancelled (in dollars per share)	$ 71.35
2012 Plan
Options, Outstanding Number [Roll Forward]
Beginning balance (in shares)	22,866,438	22,237,484
Stock options granted (in shares)	172,031	4,722,404
Stock options exercised (in shares)	(6,815,098)	(3,117,320)
Stock options cancelled (in shares)	(1,181,482)	(976,130)
Ending balance (in shares)	15,260,506	22,866,438	22,237,484
Exercisable as of April 30, 2020 (in shares)	8,007,248
Options Outstanding, Weighted Average Exercise Price [Abstract]
Beginning balance (in dollars per share)	$ 11.90	$ 8.65
Stock options granted (in dollar per share)	81.39	23.27
Stock options exercised (in dollars per share)	9.01	5.95
Stock options cancelled (in dollars per share)	15.81	11.78
Ending balance (in dollars per share)	14.17	$ 11.90	$ 8.65
Exercisable as of April 30, 2020 (in dollars per share)	$ 11.29
Remaining Contractual Term (in years)
Remaining Contractual Term (in years)	7 years 3 months 7 days	7 years 11 months 23 days	8 years 3 months 21 days
Exercisable, Remaining Contractual Term (in years)	6 years 9 months 18 days
Aggregate Intrinsic Value
Beginning balance	$ 1,684,106	$ 98,365
Ending balance	767,795	$ 1,684,106	$ 98,365
Exercisable as of April 30, 2020	$ 424,133