Shareholders' Equity (Company's Common Share Repurchase And Issuance Activity) (Details) (USD $)	3 Months Ended
Apr. 30, 2013
Increase (Decrease) in Treasury Stock [Roll Forward]
Treasury stock, beginning balance, Shares	21,436,566
Treasury stock, beginning balance, Weighted-average price per share	$ 42.26
Shares of treasury stock reissued	(210,896)
Treasury stock, ending balance, Shares	21,225,670
Treasury stock, ending balance, Weighted-average price per share	$ 42.26

Number of shares held for each class of treasury stock.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 30

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6405813&loc=d3e23239-112655

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 43

-Section B

-Paragraph 7, 11A

-Chapter 1

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Name:	us-gaap_TreasuryStockNumberOfSharesHeld
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant