Interest expense, net (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2017	Oct. 31, 2016	Oct. 31, 2017	Oct. 31, 2016
Interest Income (Expense), Net [Abstract]
Interest expense	$ 225	$ 164	$ 583	$ 556
Interest income	(32)	(52)	(76)	(121)
Interest expense, net	$ 193	$ 112	$ 507	$ 435