Fair Value Measurements Activity Between Levels of the Fair Value Hierarchy, Assets (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
Mar. 31, 2013	Mar. 25, 2012
Auction Rate Securities [Member]
Activity for Marketable Securities Classified Within Level 3 of the Valuation Hierarchy [Roll Forward]
Beginning balance of Level 3	$ 118	$ 124
Total realized and unrealized gains or losses [Abstract]
Included in investment income, net	0	0
Included in other comprehensive income	1	0
Purchases	0	0
Sales	0	0
Settlements	(35)	(4)
Transfers into Level 3	0	0
Ending balance of Level 3	84	120
Other Marketable Securities [Member]
Activity for Marketable Securities Classified Within Level 3 of the Valuation Hierarchy [Roll Forward]
Beginning balance of Level 3	203	27
Total realized and unrealized gains or losses [Abstract]
Included in investment income, net	3	1
Included in other comprehensive income	3	2
Purchases	127	88
Sales	(6)	0
Settlements	(36)	(8)
Transfers into Level 3	18	5
Ending balance of Level 3	$ 312	$ 115

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Amount of gain (loss) recognized in earnings, arising from assets measured at fair value on a recurring basis using unobservable inputs (level 3).

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- Definition

Amount of gain (loss) recognized in other comprehensive income, arising from assets measured at fair value on a recurring basis using unobservable inputs (level 3).

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- Definition

Purchases that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy.

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- Definition

Sales that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy.

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- Definition

Settlements that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy.

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- Definition

Transfers into assets measured at fair value and categorized within Level 3 of the fair value hierarchy that have taken place during the period.

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- Definition

This element represents an asset measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 157

-Paragraph 32

-Subparagraph c

-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.

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