Interest expense, net (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2016	Oct. 31, 2015	Oct. 31, 2016	Oct. 31, 2015
Interest Income (Expense), Net [Abstract]
Interest expense	$ 164	$ 247	$ 556	$ 615
Interest income	(52)	(120)	(121)	(405)
Interest expense, net	$ 112	$ 127	$ 435	$ 210