Fair Value Measurements, Valuation Techniques (Details) (Recurring, Level 3, USD $) In Millions, unless otherwise specified	3 Months Ended
Jul. 26, 2013	Jul. 27, 2012
Reconciliation of the beginning and ending balances of items measured at fair value on a recurring basis that used significant unobservable inputs
Beginning balance	$ 127	$ 172
Total unrealized gains/(losses) included in other comprehensive income	5	2
Settlements		(1)
Ending balance	132	173
Corporate Debt Securities
Reconciliation of the beginning and ending balances of items measured at fair value on a recurring basis that used significant unobservable inputs
Beginning balance	10	10
Total unrealized gains/(losses) included in other comprehensive income	0	0
Settlements		0
Ending balance	10	10
Auction Rate Securities
Reconciliation of the beginning and ending balances of items measured at fair value on a recurring basis that used significant unobservable inputs
Beginning balance	103	127
Total unrealized gains/(losses) included in other comprehensive income	4	2
Settlements		0
Ending balance	107	129
Auction Rate Securities \| Discounted Cash Flow
Fair Value Inputs
Illiquidity Premium	6.00%
Auction Rate Securities \| Discounted Cash Flow \| Minimum
Fair Value Inputs
Years to Principal Recovery	2 years
Auction Rate Securities \| Discounted Cash Flow \| Maximum
Fair Value Inputs
Years to Principal Recovery	12 years
Auction Rate Securities \| Discounted Cash Flow \| Weighted Average
Fair Value Inputs
Years to Principal Recovery	3 years
Mortgage Backed Securities
Reconciliation of the beginning and ending balances of items measured at fair value on a recurring basis that used significant unobservable inputs
Beginning balance	14	29
Total unrealized gains/(losses) included in other comprehensive income	1	0
Settlements		(1)
Ending balance	15	28
Other Asset-backed Securities
Reconciliation of the beginning and ending balances of items measured at fair value on a recurring basis that used significant unobservable inputs
Beginning balance	0	6
Total unrealized gains/(losses) included in other comprehensive income	0	0
Settlements		0
Ending balance	$ 0	$ 6

Illiquidity premium used as an input to measure fair value.

No definition available.

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- Definition

Number of years to principal recovery, used as an input to measure fair value.

+ References

No definition available.

+ Details

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- Details

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- Details

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Balance Type:	na
Period Type:	duration

- 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).

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- 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.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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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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