Investments (Maturities Of Fixed Income Securities) (Detail) (USD $) In Millions, unless otherwise specified	Jul. 27, 2013
Schedule of Investments [Line Items]
Amortized Cost	$ 39,867
Fair Value	39,888
Less Than 1 Year
Schedule of Investments [Line Items]
Amortized Cost	15,903
Fair Value	15,918
Due In 1 To 2 Years
Schedule of Investments [Line Items]
Amortized Cost	11,115
Fair Value	11,144
Due In 2 To 5 Years
Schedule of Investments [Line Items]
Amortized Cost	12,706
Fair Value	12,681
Due After 5 Years
Schedule of Investments [Line Items]
Amortized Cost	143
Fair Value	$ 145