Investments (Summary Of Available-For-Sale Investments) (Details) (USD $) In Millions	Jul. 30, 2011		Jul. 31, 2010
Amortized Cost	$ 36,135		$ 34,746
Gross Unrealized Gains	810		609
Gross Unrealized Losses	(22)		(75)
Fair Value	36,923		35,280
U.S. Government Securities [Member]
Amortized Cost	19,087		16,570
Gross Unrealized Gains	52		42
Fair Value	19,139		16,612
U.S. Government Agency Securities [Member]
Amortized Cost	8,742	[1]	13,511	[1]
Gross Unrealized Gains	35	[1]	68	[1]
Gross Unrealized Losses	(1)	[1]
Fair Value	8,776	[1]	13,579	[1]
Non-U.S. Government And Agency Securities [Member]
Amortized Cost	3,119	[2]	1,452
Gross Unrealized Gains	14	[2]	15
Gross Unrealized Losses	(1)	[2]
Fair Value	3,132	[2]	1,467
Corporate Debt Securities [Member]
Amortized Cost	4,333		2,179
Gross Unrealized Gains	65		64
Gross Unrealized Losses	(4)		(21)
Fair Value	4,394		2,222
Asset-Backed Securities [Member]
Amortized Cost	120		145
Gross Unrealized Gains	5		9
Gross Unrealized Losses	(4)		(5)
Fair Value	121		149
Total Fixed Income Securities [Member]
Amortized Cost	35,401		33,857
Gross Unrealized Gains	171		198
Gross Unrealized Losses	(10)		(26)
Fair Value	35,562		34,029
Publicly Traded Equity Securities [Member]
Amortized Cost	734		889
Gross Unrealized Gains	639		411
Gross Unrealized Losses	(12)		(49)
Fair Value	$ 1,361		$ 1,251

[1] Includes corporate securities that are guaranteed by the Federal Deposit Insurance Corporation (FDIC).

[2] Includes agency and corporate securities that are guaranteed by non-U.S. governments.