Derivative Instruments (Offsetting of Derivative Assets and Liabilities) (Details) - USD ($) $ in Millions	Jul. 25, 2015	Jul. 26, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross Amount of Recognized Assets	$ 218	$ 160
Gross Amount Offset in Consolidated Balance Sheet	0	0
Net Amount Presented in Consolidated Balance Sheet	218	160
Gross Derivative Amount with Legal Right to Offset	(12)	(39)
Cash Collateral Received	(124)	(60)
Net Amount	82	61
Gross Amount of Recognized Liabilities	12	67
Gross Amount Offset in Consolidated Balance Sheet	0	0
Net Amount Presented on Consolidated Balance Sheet	12	67
Gross Derivative Amount with Legal Right to Offset	(12)	(39)
Cash Collateral Pledged	0	(1)
Net Amount	$ 0	$ 27