Interest expense, net (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2014	Oct. 31, 2013
Interest expense, net [Abstract]
Interest expense	$ 432	$ 409	$ 1,175	$ 1,504
Interest income	(139)	(133)	(382)	(422)
Interest expense, net	$ 293	$ 276	$ 793	$ 1,082