Segment Information (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Apr. 30, 2013	Apr. 30, 2012	Jan. 31, 2013
Geographic segment data
Net Sales	$ 110,010	$ 103,655
Operating Income / (Loss)	10,005	8,488
Total Assets	515,379	493,040	526,362
Long-Lived Assets	46,289	33,567	44,501
United States
Geographic segment data
Net Sales	58,477	50,914
Operating Income / (Loss)	2,435	(5,051)
Total Assets	195,836	198,576	208,273
Long-Lived Assets	25,938	27,425	26,682
International
Geographic segment data
Net Sales	51,533	52,741
Operating Income / (Loss)	7,570	13,539
Total Assets	319,543	294,464	318,089
Long-Lived Assets	$ 20,351	$ 6,142	$ 17,819