Significant accounting policies Long lived assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 4,900	$ 5,300
Land, buildings and improvements	22,796	22,330
Machinery and equipment	47,009	44,538
Furniture, office equipment and computer systems	4,504	4,704
Transportation equipment	3,490	3,690
Subtotal	77,799	75,262
Less accumulated depreciation	43,290	38,987
Property, plant and equipment, net of accumulated depreciation	$ 34,509	$ 36,275
Impairment of Tangible Assets, Other Descriptors	there was no impairment of long-lived assets