Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ (44,792)	$ (30,447)	$ 18,852
Other comprehensive income (loss), net of tax:
Unrealized gains (losses) on investments	671	376	(209)
Other comprehensive income (loss), net of tax	671	376	(209)
Comprehensive income (loss)	$ (44,121)	$ (30,071)	$ 18,643