Other intangible assets with definite lives (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 30, 2016	Apr. 30, 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	$ 2,599		$ 2,586
Accumulated amortization	2,346		$ 2,335
Amortization expense, next twelve months	35
Amortization expense, year two	41
Amortization expense, year three	32
Amortization expense, year four	29
Amortization expense, year five	23
Amortization expense, thereafter	93
Patent amortization expense	$ 11	$ 13