Income taxes Income taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2016	Jul. 31, 2015
Income tax [Abstract]
effective income tax rate from continuing operations	55.60%	17.30%	16.10%	7.40%
Unrecognized tax benefits	$ 143		$ 143
Unrecognized tax benefits, income tax penalties and interest expense	1
Unrecognized tax benefits, income tax penalties and interest accrued	$ 47		$ 47
Income Tax Contingency [Line Items]
Income Tax Examination, Description			IRS began an audit of the fiscal year ended January 31, 2015