Income Taxes - Significant Components of Deferred Income Tax Assets (Details) - USD ($) $ in Thousands	Jan. 31, 2021	Jan. 31, 2020
Deferred Tax Assets, Net [Abstract]
Net operating loss carryforwards	$ 341,487	$ 37,507
Research and development credit carryforwards	12,191	5,701
Stock-based compensation	37,255	4,145
Accruals and reserves	29,195	11,586
Deferred revenue	6,565	5,234
Operating lease liabilities	27,842	17,716
Total deferred tax assets	454,535	81,889
Valuation allowance	(335,051)	(36,353)
Total deferred tax assets net of valuation allowance	119,484	45,536
Deferred Tax Liabilities, Net [Abstract]
Property and equipment and intangible assets	(17,229)	(6,744)
Deferred contract acquisition costs	(76,593)	(21,156)
Operating right-of-use assets	(25,550)	(16,453)
Total deferred tax liabilities	(119,372)	(44,353)
Net deferred tax assets	$ 112	$ 1,183