Derivative Instruments (Offsetting of Derivative Assets and Liabilities) (Details) - USD ($) $ in Millions	Oct. 29, 2016	Jul. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross Amount of Recognized, Assets	$ 292	$ 385
Gross Amounts Offset, Assets	0	0
Net Amounts Presented, Assets	292	385
Gross Derivative Amounts, Assets	(30)	(23)
Cash Collateral, Assets	(242)	(305)
Net Amount, Assets	20	57
Gross Amount of Recognized, Liabilities	85	54
Gross Amounts Offset, Liabilities	0	0
Net Amount Presented, Liabilities	85	54
Gross Derivative Amounts, Liabilities	(30)	(23)
Cash Collateral, Liabilities	0	0
Net Amount, Liabilities	$ 55	$ 31