Stockholders Equity Stockholders' Equity (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2011
Stockholders Equity Note [Line Items]
Preferred stock, shares authorized	2.0	2.0
Repurchase and retirement of common shares (in shares)			(9.0)
Board Of Director Approved June 2012 [Member]
Stockholders Equity Note [Line Items]
Common Stock shares remained available for repurchase under repurchase plans	30.0
Common Stock Repurchase Program
Stockholders Equity Note [Line Items]
Repurchase and retirement of common shares (in shares)	(12.5)	(9.7)
Repurchased shares of its common stock on the open market, average repurchase price per share	$ 34.50	$ 33.71	$ 31.13
Common Stock shares remained available for repurchase under repurchase plans	32.2