CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2020	Oct. 31, 2019
Statement of Comprehensive Income [Abstract]
Net loss	$ (168,889)	$ (88,057)	$ (340,167)	$ (265,281)
Other comprehensive income (loss):
Change in unrealized gains on investments, net of tax	(771)	170	159	238
Comprehensive loss	$ (169,660)	$ (87,887)	$ (340,008)	$ (265,043)