Investments (Available-For-Sale Investments With Gross Unrealized Losses) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Jul. 27, 2013	Jul. 28, 2012
Schedule of Investments [Line Items]
Fair value of investment securities with unrealized losses less than 12 months	$ 12,573	$ 6,127
Gross unrealized losses, less than 12 months	(70)	(12)
Fair value of investment securities with unrealized losses12 months or greater	4	34
Gross unrealized losses, 12 months or greater	0	(3)
Fair value of investment securities with unrealized losses	12,577	6,161
Total gross unrealized losses	(70)	(15)
Publicly Traded Equity Securities
Schedule of Investments [Line Items]
Fair value of investment securities with unrealized losses less than 12 months	278	167
Gross unrealized losses, less than 12 months	(4)	(8)
Fair value of investment securities with unrealized losses12 months or greater	0	20
Gross unrealized losses, 12 months or greater	0	(3)
Fair value of investment securities with unrealized losses	278	187
Total gross unrealized losses	(4)	(11)
Total Fixed Income Securities
Schedule of Investments [Line Items]
Fair value of investment securities with unrealized losses less than 12 months	12,295	5,960
Gross unrealized losses, less than 12 months	(66)	(4)
Fair value of investment securities with unrealized losses12 months or greater	4	14
Gross unrealized losses, 12 months or greater	0	0
Fair value of investment securities with unrealized losses	12,299	5,974
Total gross unrealized losses	(66)	(4)
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	7,865	5,357
Gross unrealized losses, less than 12 months	(13)	(1)
Fair value of investment securities with unrealized losses12 months or greater	0	0
Gross unrealized losses, 12 months or greater	0	0
Fair value of investment securities with unrealized losses	7,865	5,357
Total gross unrealized losses	(13)	(1)
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	294
Gross unrealized losses, less than 12 months	(1)
Fair value of investment securities with unrealized losses12 months or greater	0
Gross unrealized losses, 12 months or greater	0
Fair value of investment securities with unrealized losses	294
Total gross unrealized losses	(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	432
Gross unrealized losses, less than 12 months	(2)
Fair value of investment securities with unrealized losses12 months or greater	0
Gross unrealized losses, 12 months or greater	0
Fair value of investment securities with unrealized losses	432
Total gross unrealized losses	(2)
Total Fixed Income Securities | Corporate Debt Securities
Schedule of Investments [Line Items]
Fair value of investment securities with unrealized losses less than 12 months	3,704	603
Gross unrealized losses, less than 12 months	(50)	(3)
Fair value of investment securities with unrealized losses12 months or greater	4	14
Gross unrealized losses, 12 months or greater	0	0
Fair value of investment securities with unrealized losses	3,708	617
Total gross unrealized losses	$ (50)	$ (3)