Investments (Summary Of Available-For-Sale Investments) (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
	Apr. 26, 2014	Jul. 27, 2013
Schedule of Investments [Line Items]
Amortized Cost	$ 43,485	$ 41,930
Gross Unrealized Gains	768	825
Gross Unrealized Losses	(25)	(70)
Fair Value	44,228	42,685
Publicly Traded Equity Securities
Schedule of Investments [Line Items]
Amortized Cost	1,314	2,063
Gross Unrealized Gains	652	738
Gross Unrealized Losses	(7)	(4)
Fair Value	1,959	2,797
Fixed Income Investments [Member]
Schedule of Investments [Line Items]
Amortized Cost	42,171	39,867
Gross Unrealized Gains	116	87
Gross Unrealized Losses	(18)	(66)
Fair Value	42,269	39,888
Fixed Income Investments [Member] | US Government Securities[Member]
Schedule of Investments [Line Items]
Amortized Cost	31,675	27,814
Gross Unrealized Gains	34	22
Gross Unrealized Losses	(6)	(13)
Fair Value	31,703	27,823
Fixed Income Investments [Member] | US Government Agencies Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	1,060	3,083
Gross Unrealized Gains	2	7
Gross Unrealized Losses	(1)	(1)
Fair Value	1,061	3,089
Fixed Income Investments [Member] | Non-US Government and Agency Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	819	1,094
Gross Unrealized Gains	2	3
Gross Unrealized Losses	(1)	(2)
Fair Value	820	1,095
Fixed Income Investments [Member] | Corporate Debt Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	8,050	7,876
Gross Unrealized Gains	75	55
Gross Unrealized Losses	(10)	(50)
Fair Value	8,115	7,881
Fixed Income Investments [Member] | U.S. agency mortgage-backed Securities
Schedule of Investments [Line Items]
Amortized Cost	567
Gross Unrealized Gains	3
Gross Unrealized Losses	0
Fair Value	$ 570