Derivative Instruments (Offsetting of Derivative Assets and Liabilities) (Details) - USD ($) $ in Millions	Jan. 26, 2019	Jul. 28, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross Amount of Recognized, Assets	$ 23	$ 2
Gross Amounts Offset, Assets	0	0
Net Amounts Presented, Assets	23	2
Gross Derivative Amounts, Assets	(12)	(2)
Cash Collateral, Assets	(11)	0
Net Amount, Assets	0	0
Gross Amount of Recognized, Liabilities	40	74
Gross Amounts Offset, Liabilities	0	0
Net Amount Presented, Liabilities	40	74
Gross Derivative Amounts, Liabilities	(12)	(2)
Cash Collateral, Liabilities	(19)	(53)
Net Amount, Liabilities	$ 9	$ 19

Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

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Amount of obligation to return securities collateral under master netting arrangements that have not been offset against derivative assets.

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