Other intangible assets with definite lives (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2016	Jul. 31, 2015	Jan. 31, 2016
Other intangible assets with definite lives [Abstract]
Finite-Lived Intangible Assets, Amortization Method			Patents are capitalized and amortized on a straight-line basis over a period not to exceed the legal lives of the patents.
Finite Lived Intangible Assets, Intent or Ability to Renew or Extend Arrangement			The Company expenses costs incurred to renew or extend the term of intangible assets
Gross patents	$ 2,612		$ 2,612		$ 2,586
Accumulated amortization	2,357		2,357		$ 2,335
Amortization expense, next twelve months	23		23
Amortization expense, year two	42		42
Amortization expense, year three	34		34
Amortization expense, year four	31		31
Amortization expense, year five	24		24
Amortization expense, thereafter	101		101
Patent amortization expense	$ 11	$ 13	$ 22	$ 26