Equity - Shares Outstanding (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Jan. 31, 2020	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018
Shares Available for Grant
Shares available for grant, beginning (in shares)		412,401	5,479,974	18,692,404
Shares authorized (in shares)		54,970,187	33,799,630	11,322,700
Shares ceased to be available for issuance (in shares)		(15,696,031)
Options granted (in shares)		(876,961)	(46,934,532)	(25,229,343)
Options forfeited (in shares)		3,406,764	7,831,769	1,644,213
Repurchase of unvested common stock (in shares)		40,000	252,260
Shares available for grant, ending (in shares)	412,401	32,871,367	412,401	5,479,974	18,692,404
Number of Options Outstanding
Shares outstanding, beginning (in shares)		80,903,200	51,535,443	33,242,864
Options granted (in shares)		876,961	46,934,532	25,229,343
Options exercised (in shares)		(13,798,741)	(9,735,006)	(5,292,551)
Options forfeited (in shares)		(3,406,764)	(7,831,769)	(1,644,213)
Shares outstanding, ending (in shares)	80,903,200	64,574,656	80,903,200	51,535,443	33,242,864
Weighted- Average Exercise Price
Shares outstanding, beginning balance (in dollars per share)		$ 6.21	$ 2.63	$ 1.03
Granted (in dollars per share)		34.83	9.21	4.41
Exercises (in dollars per share)		3.90	3.47	1.14
Forfeited (in dollars per share)		7.04	4.07	2.23
Shares outstanding, ending balance (in dollars per share)	$ 6.21	$ 7.04	$ 6.21	$ 2.63	$ 1.03
Weighted-average remaining contractual life	8 years 7 months 6 days	7 years 8 months 12 days		8 years 9 months 18 days	8 years 9 months 18 days
Aggregate Intrinsic Value (in thousands)
Aggregate intrinsic value	$ 1,546,313	$ 17,138,896	$ 1,546,313	$ 287,993	$ 98,314
Vested and exercisable (in shares)		27,056,647
Vested and exercisable, weighted average share price (in dollars per share)		$ 5.46
Vested and exercisable, weighted average remaining contractual life		7 years 2 months 12 days
Vested and exercisable, intrinsic value		$ 7,223,808
RSUs
Shares Available for Grant
RSU's granted (in shares)		(9,552,687)	(16,700)	(950,000)
RSU's forfeited (in shares)		167,694