Investments (Summary Of Available-For-Sale Investments) (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended
	Jan. 25, 2014	Jul. 27, 2013
Schedule of Investments [Line Items]
Amortized Cost	$ 40,920	$ 41,930
Gross Unrealized Gains	831	825
Gross Unrealized Losses	(25)	(70)
Fair Value	41,726	42,685
Publicly Traded Equity Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	1,280	2,063
Gross Unrealized Gains	719	738
Gross Unrealized Losses	(4)	(4)
Fair Value	1,995	2,797
Fixed Income Investments [Member]
Schedule of Investments [Line Items]
Amortized Cost	39,640	39,867
Gross Unrealized Gains	112	87
Gross Unrealized Losses	(21)	(66)
Fair Value	39,731	39,888
Fixed Income Investments [Member] | US Government Securities[Member]
Schedule of Investments [Line Items]
Amortized Cost	29,166	27,814
Gross Unrealized Gains	30	22
Gross Unrealized Losses	(5)	(13)
Fair Value	29,191	27,823
Fixed Income Investments [Member] | US Government Agencies Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	1,307	3,083
Gross Unrealized Gains	2	7
Gross Unrealized Losses	0	(1)
Fair Value	1,309	3,089
Fixed Income Investments [Member] | Non-US Government and Agency Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	687	1,094
Gross Unrealized Gains	2	3
Gross Unrealized Losses	(1)	(2)
Fair Value	688	1,095
Fixed Income Investments [Member] | Corporate Debt Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	8,031	7,876
Gross Unrealized Gains	74	55
Gross Unrealized Losses	(15)	(50)
Fair Value	8,090	7,881
Fixed Income Investments [Member] | U.S. agency mortgage-backed Securities
Schedule of Investments [Line Items]
Amortized Cost	449
Gross Unrealized Gains	4
Gross Unrealized Losses	0
Fair Value	$ 453