Shareholders' Equity (Stock Repurchase Program) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	6 Months Ended
	Jan. 24, 2015
Stockholders' Equity Note [Abstract]
Cumulative Shares Repurchased, Beginning balance (in shares)	4,288
Repurchase of Common Stock During Period (in shares)	85	[1]
Cumulative Shares Repurchased, Ending balance (in shares)	4,373
Cumulative Weighted-Average Price per Share, Beginning balance, dollars per share	$ 20.63
Repurchase of common stock under the stock repurchase program, Weighted-Average Price per Share, dollars per share	$ 26.15
Cumulative Weighted-Average Price per Share, Ending balance, dollars per share	$ 20.73
Cumulative Amount Repurchased, Beginning balance	$ 88,445
Stock Repurchased During the Period, Shares	2,221	[1]
Cumulative Amount Repurchased, Ending balance	$ 90,666

[1] Includes stock repurchases of $150 million, which were pending settlement as of January 24, 2015. There were $126 million of stock repurchases that were pending settlement as of July 26, 2014.