Available-for-Sale Debt Investments and Equity Investments (Maturities of Fixed Income Securities) (Details) - USD ($) $ in Millions	Jan. 26, 2019	Jul. 28, 2018
Debt Securities, Available-for-sale, Amortized Cost, Fiscal Year Maturity [Abstract]
Within 1 year	$ 10,131
After 1 year through 5 years	17,704
After 5 years through 10 years	1,568
After 10 years	15
Mortgage-backed securities with no single maturity	1,475
Amortized Cost	30,893	$ 37,512
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Within 1 year	10,104
After 1 year through 5 years	17,426
After 5 years through 10 years	1,507
After 10 years	15
Mortgage-backed securities with no single maturity	1,434
Total	$ 30,486	$ 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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