Impairment of long-lived assets (Details) - USD ($) $ in Thousands	6 Months Ended
	Jul. 31, 2018	Jan. 31, 2018
Tangible Asset Impairment Charges [Abstract]
New Date of Annual Goodwill Impairment Test	impairment assessment of goodwill annually as of January 31
Impairment of long-lived assets	There was no impairment of long-lived assets for the three and six months ended July 31, 2018 and 2017
Goodwill recognized, description	allocated between intangible assets and the net tangible assets of the acquired business with the residual of the purchase price recorded as goodwill
Goodwill	$ 2,287	$ 2,423
Goodwill, Period Increase (Decrease)	$ (136)
Goodwill no impairment	There was no impairment of goodwill for the three and six months ended July 31, 2018 and 2017.