Net Income per Common Share - Reconciliation between basic and diluted net income per share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Apr. 30, 2016	Apr. 30, 2015
Earnings Per Share [Abstract]
Net income	$ 2,771	$ 6,760
Basic net income per share:
Basic common shares	45,549	44,965
Basic net income per share (in dollars per share)	$ 0.06	$ 0.15
Diluted net income per share:
Basic common shares	45,549	44,965
Restricted stock awards and stock options	1,393	1,245
Diluted common shares	46,942	46,210
Diluted net income per share (in dollars per share)	$ 0.06	$ 0.15