Financial Instruments (Derivatives Designated as Fair Value Hedges) (Details) (Interest Rate Swaps [Member], Interest Expense [Member], USD $) In Millions	3 Months Ended	9 Months Ended
May 01, 2011	May 02, 2010	May 01, 2011	May 02, 2010
Interest Rate Swaps [Member] \| Interest Expense [Member]
Amount of Gain (Loss) Recognized in Earnings on Derivatives	$ (4)	$ (2)	$ (11)	$ 3
Amount of Gain (Loss) Recognized in Earnings on Hedged Items	$ 4	$ 2	$ 11	$ (3)

The amount recognized in earnings related to the change in fair value during the period of the hedged item in a fair value hedge.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 45
-Subparagraph a(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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 25
-Section 50
-Paragraph 1
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=6886632&loc=d3e76258-113986

Name:	us-gaap_ChangeInUnrealizedGainLossOnHedgedItemInFairValueHedge
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration