Stock-Based Compensation and Stockholders equity Dividends (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended					9 Months Ended		0 Months Ended
	Oct. 31, 2013	Jul. 31, 2013	Apr. 30, 2013	Oct. 31, 2012	Jul. 31, 2010	Oct. 31, 2013	Oct. 31, 2012	Nov. 21, 2013 Subsequent Event
Dividends Declared [Line Items]
Common stock dividend per share annual amount			$ 0.18
Dividends payable, date declared	Aug. 22, 2013	May 23, 2013	Mar. 07, 2013					Nov. 21, 2013
Dividends payable, date of record	Sep. 10, 2013	Jun. 10, 2013	Mar. 22, 2013		Jul. 06, 2010			Dec. 10, 2013
Dividends payable, date to be paid	Sep. 30, 2013	Jul. 01, 2013	Apr. 10, 2013					Jan. 02, 2014
Cash dividends declared per common share	$ 0.045	$ 0.045	$ 0.045	$ 0.000		$ 0.135	$ 0.000	$ 0.045
Dividends paid	$ (5,096)	$ (5,079)	$ (5,064)			$ (15,239)	$ 0