Investments (Summary Of Available-For-Sale Investments) (Details) - USD ($) $ in Millions	Apr. 30, 2016	Jul. 25, 2015
Available-for-sale investments: [Line Items]
Amortized Cost	$ 54,242	$ 53,044
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	445	566
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(70)	(71)
Fair Value	54,617	53,539
Total fixed income securities
Available-for-sale investments: [Line Items]
Amortized Cost	52,888	51,952
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	227	86
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(40)	(64)
Fair Value	53,075	51,974
Total fixed income securities \| U.S. government securities
Available-for-sale investments: [Line Items]
Amortized Cost	24,003	29,904
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	44	41
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(3)	(6)
Fair Value	24,044	29,939
Total fixed income securities \| U.S. government agency securities
Available-for-sale investments: [Line Items]
Amortized Cost	2,883	3,662
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	5	2
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0	(1)
Fair Value	2,888	3,663
Total fixed income securities \| Non-U.S. government and agency securities
Available-for-sale investments: [Line Items]
Amortized Cost	1,063	1,128
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	2	1
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0	(1)
Fair Value	1,065	1,128
Total fixed income securities \| Corporate debt securities
Available-for-sale investments: [Line Items]
Amortized Cost	23,193	15,802
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	160	34
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(37)	(53)
Fair Value	23,316	15,783
Total fixed income securities \| U.S. agency mortgage-backed securities
Available-for-sale investments: [Line Items]
Amortized Cost	1,746	1,456
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	16	8
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0	(3)
Fair Value	1,762	1,461
Publicly traded equity securities
Available-for-sale investments: [Line Items]
Amortized Cost	1,354	1,092
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	218	480
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(30)	(7)
Fair Value	$ 1,542	$ 1,565

Available For Sale Investments [Line Items]

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- Definition

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=51813488&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=49167202&loc=d3e26610-111562

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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
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