CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2016	Oct. 31, 2015	Oct. 31, 2016	Oct. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (2,821)	$ (3,531)	$ (10,117)	$ (10,869)
Other comprehensive (loss) income
Unrealized (loss) gain on short-term investments, net	(24)		1
Comprehensive loss	$ (2,845)	$ (3,531)	$ (10,116)	$ (10,869)