Correction of immaterial errors Adjustments to the previously reported balance sheet (Details) - USD ($) $ in Thousands	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Inventories, net	$ 15,625	$ 13,685
Prepaid expenses and other current assets	1,744	2,550
Total current assets	97,048	109,704
Total assets	138,123	148,074
Retained earnings	20,193	24,602	$ 24,783
Total stockholders' equity	69,028	72,800	75,839
Total liabilities and stockholders' equity	$ 138,123	148,074
Scenario, Previously Reported [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Inventories, net		14,613
Prepaid expenses and other current assets		2,345
Total current assets		110,427
Total assets		148,797
Retained earnings		25,325	25,580
Total stockholders' equity		73,523	76,636
Total liabilities and stockholders' equity		148,797
Restatement Adjustment [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Inventories, net		(928)
Prepaid expenses and other current assets		205
Total current assets		(723)
Total assets		(723)
Retained earnings		(723)	(797)
Total stockholders' equity		(723)	$ (797)
Total liabilities and stockholders' equity		$ (723)