Warranty (Details) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2017	Jan. 31, 2016
Warranty claim activity
Beginning accrued warranty balance	$ 1,000	$ 950
Provision	700	675
Provision for (benefits from) prior year	(285)	(250)
Costs incurred	(415)	(375)
Ending accrued warranty balance	$ 1,000	$ 1,000
Minimum [Member]
Warranty [Line Items]
Product warranty period	10 years
Maximum [Member]
Warranty [Line Items]
Product warranty period	10 years