Investments (Realized Net Gains (Losses) Related To Available-For-Sale Investments) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
Oct. 26, 2013	Oct. 27, 2012
Net gains (losses) on investments	$ 83	$ 27
Publicly Traded Equity Securities [Member]
Net gains (losses) on investments	75	10
Fixed Income Investments [Member]
Net gains (losses) on investments	$ 8	$ 17

This item represents the difference between the gross realized gains and losses realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. Additionally, this item would include any losses recognized for other than temporary impairments (OTTI) of the subject investments in debt and equity securities.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 9

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27357-111563

Name:	us-gaap_AvailableForSaleSecuritiesGrossRealizedGainLossNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration