Shareholders' Equity (Company's Common Share Repurchase And Issuance Activity) (Details) (USD $)	9 Months Ended
	Oct. 31, 2011
Shareholders' Equity [Abstract]
Treasury stock held at January 31, 2011, Shares	12,517,538
Treasury stock held at January 31, 2011, Weighted-average price per share	$ 37.28
Shares of common stock repurchased under share repurchase program, Shares	6,442,542
Shares of common stock repurchased under share repurchase program, Weighted-average price per share	$ 46.57
Shares of treasury stock reissued	(992,007)
Shares of treasury stock reissued, Weighted-average price per share	$ 38.34
Treasury stock held at October 31, 2011, Shares	17,968,073
Treasury stock held at October 31, 2011, Weighted-average price per share	$ 40.55