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	$ (72,764)	$ (63,495)	$ (190,526)	$ (158,441)
Other comprehensive income (loss):
Net change in unrealized gains or losses on available-for-sale securities	(2,226)	227	1,344	616
Foreign currency translation adjustments	(724)	1,561	335	(162)
Other comprehensive income (loss)	(2,950)	1,788	1,679	454
Comprehensive loss	$ (75,714)	$ (61,707)	$ (188,847)	$ (157,987)