Income taxes Income tax disclosure (Details) - USD ($) $ in Thousands	Jan. 31, 2017	Jan. 31, 2016
Components of deferred income tax assets
U.S. Federal NOL carryforward	$ 9,348	$ 3,044
Deferred compensation	346	2,382
Research tax credit	2,703	2,057
Foreign NOL carryforward	186	231
Foreign tax credit	4,695	2,861
Stock compensation	804	1,061
Other accruals not yet deducted	514	438
State NOL carryforward	1,877	1,419
Accrued commissions and incentives	765	723
Inventory valuation allowance	110	73
Other	4	116
Deferred tax assets, gross	21,352	14,405
Valuation allowance	(18,437)	(13,333)
Total deferred tax assets, net of valuation allowances	2,915	1,072
Components of the deferred income tax liability
Depreciation	(2,778)	(633)
Foreign subsidiaries unremitted earnings	(1,750)	(412)
Prepaid	(69)	(88)
Total deferred tax liabilities	(4,597)	(1,133)
Deferred tax liabilities, net	(1,682)	(61)
Balance sheet classification
Deferred tax assets - long-term	147	99
Deferred tax liabilities - long-term	(1,829)	$ (160)
Middle East [Member]
Components of deferred income tax assets
Foreign tax credit	$ 100