Interest expense, net (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2014	Jul. 31, 2013
Interest expense, net [Abstract]
Interest expense	$ 391	$ 510	$ 743	$ 1,095
Interest income	(128)	(125)	(243)	(289)
Interest expense, net	$ 263	$ 385	$ 500	$ 806