Investments (Maturities Of Fixed Income Securities) (Details) (USD $) In Millions, unless otherwise specified	Jan. 24, 2015
Schedule of Investments [Line Items]
Amortized Cost	$ 46,274
Fair Value	46,377
Less than 1 year
Schedule of Investments [Line Items]
Amortized Cost	15,355
Fair Value	15,362
Due in 1 to 2 years
Schedule of Investments [Line Items]
Amortized Cost	14,963
Fair Value	14,995
Due in 2 to 5 years
Schedule of Investments [Line Items]
Amortized Cost	14,383
Fair Value	14,431
Due after 5 years
Schedule of Investments [Line Items]
Amortized Cost	1,573
Fair Value	$ 1,589