Derivative Instruments (Offsetting of Derivative Assets and Liabilities) (Details) - USD ($) $ in Millions	Oct. 24, 2015	Jul. 25, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross Amount of Recognized Assets	$ 343	$ 218
Gross Amounts Offset in Consolidated Balance Sheets	0	0
Net Amount Presented on Consolidated Balance Sheets	343	218
Gross Derivative Amounts with Legal Rights to Offset	(14)	(12)
Cash Collateral Received	(225)	(124)
Net Amount	104	82
Gross Amount of Recognized Liabilities	14	12
Gross Amounts Offset in Consolidated Balance Sheets	0	0
Net Amount Presented on Consolidated Balance Sheets	14	12
Gross Derivative Amounts with Legal Rights to Offset	(14)	(12)
Cash Collateral Pledged	0	0
Net Amount	$ 0	$ 0