Investments (Summary Of Available-For-Sale Investments) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Jul. 27, 2013	Jul. 28, 2012
Available-for-sale investments: [Line Items]
Amortized Cost	$ 41,930	$ 38,263
Gross Unrealized Gains	825	669
Gross Unrealized Losses	(70)	(15)
Fair Value	42,685	38,917
Publicly Traded Equity Securities
Available-for-sale investments: [Line Items]
Amortized Cost	2,063	1,107
Gross Unrealized Gains	738	524
Gross Unrealized Losses	(4)	(11)
Fair Value	2,797	1,620
Total Fixed Income Securities
Available-for-sale investments: [Line Items]
Amortized Cost	39,867	37,156
Gross Unrealized Gains	87	145
Gross Unrealized Losses	(66)	(4)
Fair Value	39,888	37,297
Total Fixed Income Securities | U.S. Government Securities
Available-for-sale investments: [Line Items]
Amortized Cost	27,814	24,201
Gross Unrealized Gains	22	41
Gross Unrealized Losses	(13)	(1)
Fair Value	27,823	24,241
Total Fixed Income Securities | U.S. Government Agency Securities
Available-for-sale investments: [Line Items]
Amortized Cost	3,083	5,367
Gross Unrealized Gains	7	21
Gross Unrealized Losses	(1)	0
Fair Value	3,089	5,388
Total Fixed Income Securities | Non-U.S. Government And Agency Securities
Available-for-sale investments: [Line Items]
Amortized Cost	1,094	1,629
Gross Unrealized Gains	3	9
Gross Unrealized Losses	(2)	0
Fair Value	1,095	1,638
Total Fixed Income Securities | Corporate Debt Securities
Available-for-sale investments: [Line Items]
Amortized Cost	7,876	5,959
Gross Unrealized Gains	55	74
Gross Unrealized Losses	(50)	(3)
Fair Value	$ 7,881	$ 6,030