Significant accounting policies Long lived assets (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2013	Jan. 31, 2012
Long lived assets [Abstract]
Depreciation expense	$ 5,806	$ 5,582
Land, buildings and improvements	37,573	36,565
Machinery and equipment	51,809	50,066
Furniture, office equipment and computer systems	13,153	12,682
Transportation equipment	198	465
Subtotal	102,733	99,778
Less accumulated depreciation and amortization	56,332	51,936
Property, plant and equipment, net of accumulated depreciation	$ 46,401	$ 47,842