Retirement plans 401K (Details) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 313	$ 405
Maximum % of each participant's salary	16.00%
Defined Contribution Plan, Description	The Company matches 100% of each participant's payroll deferral contributions up to 1% of their compensation, plus 50% of each participant's payroll deferral contributions on the next 5% of compensation
Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Maximum % of each participant's salary	1.00%