Shareholders' Equity (Company's Common Share Repurchases And Issuance Activity) (Details) (USD $)	3 Months Ended
	Apr. 30, 2012
Shareholders' Equity [Abstract]
Treasury stock held at January 31, 2012, Shares	18,166,761
Treasury stock held at January 31, 2012, Weighted-average price per share	$ 40.71
Shares of common stock repurchased under share repurchase program and other share repurchases, Shares	853,233
Shares of common stock repurchased under share repurchase program and other share repurchases, Weighted-average price per share	$ 53.48
Shares of treasury stock reissued	(458,099)
Treasury stock held at April 30, 2012, Shares	18,561,895
Treasury stock held at April 30, 2012, Weighted-average price per share	$ 41.30