Stock options Fair value assumptions (Details)	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013
Minimum [Member]
Expected volatility rate	42.12%	53.90%
Risk free interest rate	0.74%	0.74%
Expected dividend rate	0.00%	0.00%
expected term	4 years 10 months 24 days	4 years 10 months 24 days
Maximum [Member]
Expected volatility rate	65.54%	66.82%
Risk free interest rate	2.82%	3.57%
Expected dividend rate	0.00%	0.00%
expected term	5 years 8 months 12 days	5 years 8 months 12 days