Shareholders' Equity (Company's Common Share Repurchase And Issuance Activity) (Details) (USD $)	6 Months Ended
	Jul. 31, 2011
Shareholders' Equity
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	4,229,179
Shares of common stock repurchased under share repurchase program, Weighted-average price per share	$ 47.29
Shares of treasury stock reissued	(904,353)
Shares of treasury stock reissued, Weighted-average price per share	$ 38.13
Treasury stock held at July 31, 2011, Shares	15,842,364
Treasury stock held at July 31, 2011, Weighted-average price per share	$ 39.90