Business and segment information Geographic information (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013
Geographic information [Line Items]
foreign sales	0.00%	0.00%
Net sales	$ 226,835	$ 168,807
Property, plant and equipment, net of accumulated depreciation	42,541	45,582
United States
Geographic information [Line Items]
Net sales	97,311	104,830
Property, plant and equipment, net of accumulated depreciation	25,260	26,952
Middle East
Geographic information [Line Items]
Net sales	94,500	24,631
Property, plant and equipment, net of accumulated depreciation	12,751	13,204
Denmark
Geographic information [Line Items]
Property, plant and equipment, net of accumulated depreciation	4,020	4,445
Europe
Geographic information [Line Items]
Net sales	14,933	16,324
Canada
Geographic information [Line Items]
Net sales	7,591	9,771
India
Geographic information [Line Items]
Net sales	773	6,317
Property, plant and equipment, net of accumulated depreciation	510	981
Other Americas
Geographic information [Line Items]
Net sales	6,915	2,317
Other
Geographic information [Line Items]
Net sales	$ 4,812	$ 4,617