Stock Option Plans (Detail) - Schedule of Share-Based Compensation (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Apr. 30, 2013	Apr. 30, 2012
Outstanding at January 31, 2013	168,755
Outstanding at January 31, 2013 (in Dollars per share)	$ 12.46
Exercised	(43,305)
Exercised (in Dollars per share)	$ 12.82	$ 32.53
Outstanding and exercisable at April 30, 2013	125,450
Outstanding and exercisable at April 30, 2013 (in Dollars per share)	$ 12.34
Outstanding and exercisable at April 30, 2013	328 days
Outstanding and exercisable at April 30, 2013 (in Dollars)	$ 797