CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Apr. 30, 2019	Apr. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ 2,214	$ (1,340)
Other comprehensive loss:
Unrealized gain (loss) on available for sale marketable securities, net of tax	143	(82)
Comprehensive income (loss)	$ 2,357	$ (1,422)