Interest expense, net (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Oct. 31, 2013	Oct. 31, 2012	Oct. 31, 2013	Oct. 31, 2012
Interest expense, net [Abstract]
Interest expense	$ 332	$ 592	$ 1,504	$ 1,520
Interest income	(142)	(79)	(422)	(372)
Interest expense, net	$ 190	$ 513	$ 1,082	$ 1,148