Derivative Instruments (Offsetting of Derivative Assets and Liabilities) (Details) - USD ($) $ in Millions	Jan. 23, 2016	Jul. 25, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross Amount of Recognized Assets	$ 321	$ 218
Gross Amounts Offset in Consolidated Balance Sheets	0	0
Net Amount Presented on Consolidated Balance Sheets	321	218
Gross Derivative Amounts with Legal Rights to Offset	(15)	(12)
Cash Collateral Received	(255)	(124)
Net Amount	51	82
Gross Amount of Recognized Liabilities	19	12
Gross Amounts Offset in Consolidated Balance Sheets	0	0
Net Amount Presented on Consolidated Balance Sheets	19	12
Gross Derivative Amounts with Legal Rights to Offset	(15)	(12)
Cash Collateral Pledged	0	0
Net Amount	$ 4	$ 0