Derivative Instruments (Narrative) (Details) (USD $) In Millions, unless otherwise specified	Jan. 31, 2007
Summary of Derivative Instruments [Abstract]
Canadian dollar denominated intercompany loans related to cross-currency swaps	$ 470

Aggregate notional amount of all foreign currency derivatives designated as hedging instruments in cash flow hedges. Notional amount refers to the number of currency units specified in the foreign currency derivative contract.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5579245-113959

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Notional Amount

-URI http://asc.fasb.org/extlink&oid=6519104

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1B

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5580258-113959

Name:	us-gaap_NotionalAmountOfForeignCurrencyCashFlowHedgeDerivatives
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant