Investments (Available-For-Sale Investments With Gross Unrealized Losses) (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
	Apr. 26, 2014	Jul. 27, 2013
Schedule of Investments [Line Items]
Available-for-sale Securities with Unrealized Losses Less than 12 Months, Fair Value	$ 7,814	$ 12,573
Gross Unrealized Losses, Less than 12 Months	(25)	(70)
Available-for-sale Securities with Unrealized Losses 12 Months or Longer, Fair Value	63	4
Gross Unrealized Losses, 12 Months or Longer	0	0
Available-for-sale Investments with Unrealized Losses, Fair Value	7,877	12,577
Total Gross Unrealized Losses	(25)	(70)
Publicly Traded Equity Securities
Schedule of Investments [Line Items]
Available-for-sale Securities with Unrealized Losses Less than 12 Months, Fair Value	117	278
Gross Unrealized Losses, Less than 12 Months	(7)	(4)
Available-for-sale Securities with Unrealized Losses 12 Months or Longer, Fair Value	0	0
Gross Unrealized Losses, 12 Months or Longer	0	0
Available-for-sale Investments with Unrealized Losses, Fair Value	117	278
Total Gross Unrealized Losses	(7)	(4)
Total Fixed Income Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities with Unrealized Losses Less than 12 Months, Fair Value	7,697	12,295
Gross Unrealized Losses, Less than 12 Months	(18)	(66)
Available-for-sale Securities with Unrealized Losses 12 Months or Longer, Fair Value	63	4
Gross Unrealized Losses, 12 Months or Longer	0	0
Available-for-sale Investments with Unrealized Losses, Fair Value	7,760	12,299
Total Gross Unrealized Losses	(18)	(66)
Total Fixed Income Securities [Member] | US Government Securities[Member]
Schedule of Investments [Line Items]
Available-for-sale Securities with Unrealized Losses Less than 12 Months, Fair Value	5,111	7,865
Gross Unrealized Losses, Less than 12 Months	(6)	(13)
Available-for-sale Securities with Unrealized Losses 12 Months or Longer, Fair Value	8	0
Gross Unrealized Losses, 12 Months or Longer	0	0
Available-for-sale Investments with Unrealized Losses, Fair Value	5,119	7,865
Total Gross Unrealized Losses	(6)	(13)
Total Fixed Income Securities [Member] | US Government Agencies Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities with Unrealized Losses Less than 12 Months, Fair Value	396	294
Gross Unrealized Losses, Less than 12 Months	(1)	(1)
Available-for-sale Securities with Unrealized Losses 12 Months or Longer, Fair Value	3	0
Gross Unrealized Losses, 12 Months or Longer	0	0
Available-for-sale Investments with Unrealized Losses, Fair Value	399	294
Total Gross Unrealized Losses	(1)	(1)
Total Fixed Income Securities [Member] | Non-US Government and Agency Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities with Unrealized Losses Less than 12 Months, Fair Value	378	432
Gross Unrealized Losses, Less than 12 Months	(1)	(2)
Available-for-sale Securities with Unrealized Losses 12 Months or Longer, Fair Value	0	0
Gross Unrealized Losses, 12 Months or Longer	0	0
Available-for-sale Investments with Unrealized Losses, Fair Value	378	432
Total Gross Unrealized Losses	(1)	(2)
Total Fixed Income Securities [Member] | Corporate Debt Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities with Unrealized Losses Less than 12 Months, Fair Value	1,654	3,704
Gross Unrealized Losses, Less than 12 Months	(10)	(50)
Available-for-sale Securities with Unrealized Losses 12 Months or Longer, Fair Value	52	4
Gross Unrealized Losses, 12 Months or Longer	0	0
Available-for-sale Investments with Unrealized Losses, Fair Value	1,706	3,708
Total Gross Unrealized Losses	(10)	(50)
Total Fixed Income Securities [Member] | U.S. agency mortgage-backed Securities
Schedule of Investments [Line Items]
Available-for-sale Securities with Unrealized Losses Less than 12 Months, Fair Value	158
Gross Unrealized Losses, Less than 12 Months	0
Available-for-sale Securities with Unrealized Losses 12 Months or Longer, Fair Value	0
Gross Unrealized Losses, 12 Months or Longer	0
Available-for-sale Investments with Unrealized Losses, Fair Value	158
Total Gross Unrealized Losses	$ 0