CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2019
Statement of Comprehensive Income [Abstract]
Net loss	$ (539,102)	$ (348,535)	$ (178,028)
Other comprehensive income:
Foreign currency translation adjustments	118	0	0
Increase in net unrealized gains on investments, net of tax	105	200	40
Comprehensive loss	$ (538,879)	$ (348,335)	$ (177,988)