Warranty (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2017	Oct. 31, 2016	Oct. 31, 2017	Oct. 31, 2016
Warranty claim activity
Beginning balance	$ 1,000	$ 1,000	$ 1,000	$ 1,000
Provision	173	155	355	331
Costs incurred	(173)	(155)	(355)	(331)
Ending balance	$ 1,000	$ 1,000	$ 1,000	$ 1,000
Maximum [Member]
Warranty [Line Items]
Product warranty period			10 years