Investments (Available-For-Sale Investments With Gross Unrealized Losses) (Details) - USD ($) $ in Millions	Jul. 30, 2016	Jul. 25, 2015
Schedule of Investments [Line Items]
Fair value of investment securities with unrealized losses less than 12 months	$ 5,480	$ 18,599
Less Than 12 Months, Unrealized Loss	(49)	(67)
Fair value of investment securities with unrealized losses12 months or greater	1,208	318
12 Months or Greater, Unrealized Losses	(8)	(4)
Fair value of investment securities with unrealized losses	6,688	18,917
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	57	71
Publicly traded equity securities
Schedule of Investments [Line Items]
Fair value of investment securities with unrealized losses less than 12 months	188	108
Less Than 12 Months, Unrealized Loss	(40)	(7)
Fair value of investment securities with unrealized losses12 months or greater	0	2
12 Months or Greater, Unrealized Losses	0	0
Fair value of investment securities with unrealized losses	188	110
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	40	7
Total fixed income securities
Schedule of Investments [Line Items]
Fair value of investment securities with unrealized losses less than 12 months	5,292	18,491
Less Than 12 Months, Unrealized Loss	(9)	(60)
Fair value of investment securities with unrealized losses12 months or greater	1,208	316
12 Months or Greater, Unrealized Losses	(8)	(4)
Fair value of investment securities with unrealized losses	6,500	18,807
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	17	64
Total fixed income securities \| U.S. government securities
Schedule of Investments [Line Items]
Fair value of investment securities with unrealized losses less than 12 months	2,414	6,412
Less Than 12 Months, Unrealized Loss	(2)	(6)
Fair value of investment securities with unrealized losses12 months or greater	0	0
12 Months or Greater, Unrealized Losses	0	0
Fair value of investment securities with unrealized losses	2,414	6,412
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	2	6
Total fixed income securities \| U.S. government agency securities
Schedule of Investments [Line Items]
Fair value of investment securities with unrealized losses less than 12 months	144	1,433
Less Than 12 Months, Unrealized Loss	0	(1)
Fair value of investment securities with unrealized losses12 months or greater	0	0
12 Months or Greater, Unrealized Losses	0	0
Fair value of investment securities with unrealized losses	144	1,433
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	0	1
Total fixed income securities \| Non-U.S. government and agency securities
Schedule of Investments [Line Items]
Fair value of investment securities with unrealized losses less than 12 months	61	515
Less Than 12 Months, Unrealized Loss	0	(1)
Fair value of investment securities with unrealized losses12 months or greater	0	4
12 Months or Greater, Unrealized Losses	0	0
Fair value of investment securities with unrealized losses	61	519
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	0	1
Total fixed income securities \| Corporate debt securities
Schedule of Investments [Line Items]
Fair value of investment securities with unrealized losses less than 12 months	2,499	9,552
Less Than 12 Months, Unrealized Loss	(7)	(49)
Fair value of investment securities with unrealized losses12 months or greater	1,208	312
12 Months or Greater, Unrealized Losses	(8)	(4)
Fair value of investment securities with unrealized losses	3,707	9,864
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	15	53
Total fixed income securities \| Mortgage-backed Securities
Schedule of Investments [Line Items]
Fair value of investment securities with unrealized losses less than 12 months	174	579
Less Than 12 Months, Unrealized Loss	0	(3)
Fair value of investment securities with unrealized losses12 months or greater	0	0
12 Months or Greater, Unrealized Losses	0	0
Fair value of investment securities with unrealized losses	174	579
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 0	$ 3

Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563

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Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale in a continuous loss position.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563

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