Available-for-Sale Debt Investments and Equity Investments (Maturities of Fixed Income Securities) (Details) - USD ($) $ in Millions	Oct. 27, 2018	Jul. 28, 2018
Debt Securities, Available-for-sale, Amortized Cost, Fiscal Year Maturity [Abstract]
Within 1 year	$ 12,283
After 1 year through 5 years	19,248
After 5 years through 10 years	1,662
After 10 years	15
Mortgage-backed securities with no single maturity	1,481
Amortized Cost	34,689	$ 37,512
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Within 1 year	12,243
After 1 year through 5 years	18,922
After 5 years through 10 years	1,581
After 10 years	16
Mortgage-backed securities with no single maturity	1,421
Total	$ 34,183	$ 37,009

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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