Summary Of The Weighted Average Grant Date Fair Values (Detail) (USD $)	12 Months Ended
	Jan. 31, 2012	Jan. 31, 2011	Jan. 31, 2010
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Options granted	$ 5.43	$ 5.02	$ 4.06
Stock granted	$ 10.91	$ 9.61
Restricted Stock
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock granted	$ 10.91	$ 9.61	$ 8.78
Employee Stock Purchase Plans
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock granted	$ 3.19	$ 2.17	$ 2.77