Financial Instruments (Derivatives Designated As Fair-Value Hedges) (Details) (Interest Expense [Member], Interest Rate Swap [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
Oct. 27, 2013	Oct. 28, 2012
Interest Expense [Member] \| Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Earnings on Derivatives	$ (1)	$ (4)
Amount of Gain or (Loss) Recognized in Earnings on Hedged Items	$ 1	$ 4

Amount of gain (loss) from the increase (decrease) in fair value of derivative and nonderivative instruments designated as fair value hedging instruments recognized in the income statement.

Reference 1: 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_ChangeInUnrealizedGainLossOnFairValueHedgingInstruments1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration