Share Repurchases (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended	19 Months Ended
Jan. 27, 2013	Jan. 29, 2012	Jan. 29, 2012 June 2011 Program [Member]	Jan. 27, 2013 June 2011 Program [Member]
Statement [Line Items]
Authorized amount for shares repurchase				$ 1,000
Shares repurchased, shares	(2)	(5)
Shares repurchased, value	(63)	(173)	(115)
Stock Repurchase Program, Remaining Authorized Repurchase Amount				$ 750
Treasury stock retired, shares	219

Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

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-Name Accounting Principles Board Opinion (APB)

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

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-Name Accounting Standards Codification

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