Investments (Summary Of Available-For-Sale Investments) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Oct. 26, 2013	Jul. 27, 2013
Schedule of Investments [Line Items]
Amortized Cost	$ 42,154	$ 41,930
Gross Unrealized Gains	819	825
Gross Unrealized Losses	(26)	(70)
Fair Value	42,947	42,685
Publicly Traded Equity Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	1,820	2,063
Gross Unrealized Gains	696	738
Gross Unrealized Losses	(2)	(4)
Fair Value	2,514	2,797
Fixed Income Investments [Member]
Schedule of Investments [Line Items]
Amortized Cost	40,334	39,867
Gross Unrealized Gains	123	87
Gross Unrealized Losses	(24)	(66)
Fair Value	40,433	39,888
Fixed Income Investments [Member] | US Government Securities[Member]
Schedule of Investments [Line Items]
Amortized Cost	28,603	27,814
Gross Unrealized Gains	37	22
Gross Unrealized Losses	(2)	(13)
Fair Value	28,638	27,823
Fixed Income Investments [Member] | US Government Agencies Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	2,394	3,083
Gross Unrealized Gains	5	7
Gross Unrealized Losses	0	(1)
Fair Value	2,399	3,089
Fixed Income Investments [Member] | Non-US Government and Agency Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	907	1,094
Gross Unrealized Gains	3	3
Gross Unrealized Losses	(1)	(2)
Fair Value	909	1,095
Fixed Income Investments [Member] | Corporate Debt Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	7,974	7,876
Gross Unrealized Gains	73	55
Gross Unrealized Losses	(21)	(50)
Fair Value	8,026	7,881
Fixed Income Investments [Member] | U.S. agency mortgage-backed Securities
Schedule of Investments [Line Items]
Amortized Cost	456
Gross Unrealized Gains	5
Gross Unrealized Losses	0
Fair Value	$ 461