Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (14,756)	$ (10,191)	$ (30,219)	$ (27,502)
Other comprehensive income, net of tax:
Unrealized gains on investments	1,182	194	819	448
Other comprehensive income, net of tax	1,182	194	819	448
Comprehensive loss	$ (13,574)	$ (9,997)	$ (29,400)	$ (27,054)