Stock-based compensation Stock-based compensation expense (Details) (USD $)	3 Months Ended		6 Months Ended
	Jul. 31, 2013	Jul. 31, 2012	Jul. 31, 2013	Jul. 31, 2012
Stock-based compensation expense [Abstract]
Stock-based compensation expense	$ (51,000)	$ 174,000	$ 68,000	$ 260,000
unrecognized compensation expense	$ 1,100,000		$ 1,100,000
expense expected to be recognized over a period			2 years 9 months 60 days