Warranty (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2017	Jul. 31, 2016
Warranty claim activity
Beginning balance	$ 1,000	$ 1,000	$ 1,000	$ 1,000
Provision	112	47	182	176
Costs incurred	(112)	(47)	(182)	(176)
Ending balance	$ 1,000	$ 1,000	$ 1,000	$ 1,000
Maximum [Member]
Warranty [Line Items]
Product warranty period			10 years