Income taxes Income taxes (Details) - USD ($)	3 Months Ended
	Apr. 30, 2017	Apr. 30, 2016
Income Tax Disclosure [Abstract]
effective income tax rate from continuing operations	12.20%	4.00%
Unrecognized tax benefits	$ 200,000
Unrecognized tax benefits, income tax penalties and interest expense	1,200
Unrecognized tax benefits, income tax penalties and interest accrued	$ 46,800
Income Tax Contingency [Line Items]
Income Tax Examination, Description	The Internal Revenue Service, ("IRS") began an audit of the fiscal year ended January 31, 2015 in August 2016. In March 2017, the Company received an informal notice from the IRS that it had concluded the tax audit for the year ended January 31, 2015. No changes were made to the reported tax.