v2.4.0.6
Investments (Summary Of Available-For-Sale Investments) (Detail) (USD $)
In Millions, unless otherwise specified
Jul. 28, 2012
Jul. 30, 2011
Available-for-sale investments: [Line Items]    
Amortized Cost $ 38,263 $ 36,135
Gross Unrealized Gains 669 810
Gross Unrealized Losses (15) (22)
Fair Value 38,917 36,923
Publicly Traded Equity Securities
   
Available-for-sale investments: [Line Items]    
Amortized Cost 1,107 734
Gross Unrealized Gains 524 639
Gross Unrealized Losses (11) (12)
Fair Value 1,620 1,361
Total Fixed Income Securities
   
Available-for-sale investments: [Line Items]    
Amortized Cost 37,156 35,401
Gross Unrealized Gains 145 171
Gross Unrealized Losses (4) (10)
Fair Value 37,297 35,562
Total Fixed Income Securities | U.S. Government Securities
   
Available-for-sale investments: [Line Items]    
Amortized Cost 24,201 19,087
Gross Unrealized Gains 41 52
Gross Unrealized Losses (1)  
Fair Value 24,241 19,139
Total Fixed Income Securities | U.S. Government Agency Securities
   
Available-for-sale investments: [Line Items]    
Amortized Cost 5,367 8,742
Gross Unrealized Gains 21 35
Gross Unrealized Losses   (1)
Fair Value 5,388 8,776
Total Fixed Income Securities | Non-U.S. Government And Agency Securities
   
Available-for-sale investments: [Line Items]    
Amortized Cost 1,629 3,119
Gross Unrealized Gains 9 14
Gross Unrealized Losses   (1)
Fair Value 1,638 3,132
Total Fixed Income Securities | Corporate Debt Securities
   
Available-for-sale investments: [Line Items]    
Amortized Cost 5,959 4,333
Gross Unrealized Gains 74 65
Gross Unrealized Losses (3) (4)
Fair Value 6,030 4,394
Total Fixed Income Securities | Asset-Backed Securities
   
Available-for-sale investments: [Line Items]    
Amortized Cost   120
Gross Unrealized Gains   5
Gross Unrealized Losses   (4)
Fair Value   $ 121