Net Income per Common Share - Reconciliation between basic and diluted net income per share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jul. 31, 2013	Jul. 31, 2012	Jul. 31, 2013	Jul. 31, 2012
Earnings Per Share [Abstract]
Net income	$ 3,592	$ 1,362	$ 4,710	$ 514
Basic net income per share:
Basic common shares	20,305	19,995	20,234	19,928
Basic net income per share	$ 0.18	$ 0.07	$ 0.23	$ 0.03
Diluted net income per share:
Basic common shares	20,305	19,995	20,234	19,928
Restricted stock awards and stock options	448	336	452	406
Diluted common shares	20,753	20,331	20,686	20,334
Diluted net income per share	$ 0.17	$ 0.07	$ 0.23	$ 0.03