Income Taxes - Summary of Components of Deferred Tax Assets (Details) - USD ($) $ in Thousands	Apr. 30, 2020	Apr. 30, 2019
Deferred tax assets:
Accrued compensation	$ 3,267	$ 1,685
Net operating loss carryforward	208,629	84,194
Deferred revenue	3,876	0
Intangibles/assets	0	2,321
Stock-based compensation	7,203	4,089
Research and development credits	15,333	3,584
Other	3,882	1,875
Gross deferred tax assets	242,190	97,748
Less valuation allowance	(225,197)	(92,309)
Total deferred tax assets	16,993	5,439
Deferred tax liabilities:
Deferred contract acquisition costs	(8,423)	(5,878)
Intangible assets	(8,841)	0
Deferred revenue	0	(858)
Other	(218)	(674)
Gross deferred tax liabilities	(17,482)	(7,410)
Net deferred tax assets (liabilities)	$ (489)	$ (1,971)