Income taxes Income tax narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017
Components of deferred income tax assets [Line Items]
Foreign Earnings Repatriated	$ 23,200
Other Information Pertaining to Income Taxes	This income is fully offset by the use of NOL carryforwards and the current year domestic loss, resulting in no regular tax on the income.
Federal rate change, new percentage	21.00%
Federal rate change	$ 2,243	$ 0
State benefit, net of federal income tax effect	$ (440)	(103)
Federal Rate, Percent	33.83%
Federal operating loss carryforward, gross	$ 12,700
Federal operating loss carryforward expires	Jan. 31, 2031
State NOL carryforward	$ 2,157	1,574
State operating loss carryforwards, expiration dates	expire at various times from 2022 to 2031
Domestic valuation allowance, methodologies and assumptions	The Company continues to have a valuation allowance on its domestic DTAs since domestic losses continue to be generated.
Foreign tax credit	$ 9,749	$ 4,695
Tax credit carryforward, expiration date	Jan. 31, 2022
UTP penalties and interest accrued is less than	$ 100
UTP that would impact effective tax rate	$ 1,301
Income tax examination, description	The Internal Revenue Service, ("IRS"), began an audit of the fiscal year ended January 31, 2015 in August 2016. In 2017, the tax audit concluded with no change made to the reported tax
Open tax year	2014
Open tax years up to the amount of research tax credit generated	January 31, 2002 through January 31, 2009
Middle East [Member]
Components of deferred income tax assets [Line Items]
Federal operating loss carryforward, gross	$ 300