Interest expense, net (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2016	Jul. 31, 2015
Interest expense, net [Abstract]
Interest expense	$ 139	$ 172	$ 392	$ 367
Interest income	(42)	(10)	(69)	(284)
Interest expense, net	$ 97	$ 162	$ 323	$ 83