Investments (Maturities of fixed income securities) (Details) - USD ($) $ in Millions	Jul. 28, 2018	Jul. 29, 2017
Fair Value
Total, fair value	$ 37,614	$ 58,784
Fixed Income Securities
Amortized Cost
Less than 1 year, cost	12,361
Due in 1 to 2 years, cost	7,573
Due in 2 to 5 years, cost	14,290
Due after 5 years, cost	1,800
Mortgage-backed securities with no single maturity, cost	1,488
Total, Cost	37,512
Fair Value
Less than 1 year, fair value	12,316
Due in 1 to 2 years, fair Value	7,514
Due in 2 to 5 year, fair Value	14,012
Due after 5 years, fair value	1,732
Mortgage-backed securities with no single maturity, fair value	1,435
Total, fair value	$ 37,009

Available for sale securities, debt maturities, due after 5 years, cost basis

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Available for sale securities debt maturities due after 5 years, fair value

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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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