Derivative Instruments (Offsetting of Derivative Assets and Liabilities) (Details) - USD ($) $ in Millions	Oct. 28, 2017	Jul. 29, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross Amount of Recognized, Assets	$ 99	$ 149
Gross Amounts Offset, Assets	0	0
Net Amounts Presented, Assets	99	149
Gross Derivative Amounts, Assets	(14)	(4)
Cash Collateral, Assets	(57)	(81)
Net Amount, Assets	28	64
Gross Amount of Recognized, Liabilities	18	4
Gross Amounts Offset, Liabilities	0	0
Net Amount Presented, Liabilities	18	4
Gross Derivative Amounts, Liabilities	(14)	(4)
Cash Collateral, Liabilities	0	0
Net Amount, Liabilities	$ 4	$ 0