Shareholders' Equity (Stock Repurchase Program) (Details) - USD ($)	3 Months Ended
	Oct. 28, 2017	Jul. 29, 2017
Shares Repurchased
Cumulative Shares Repurchased, Beginning balance (in shares)	4,709,000,000
Repurchase of common stock under the stock repurchase program, Shares Repurchased (in shares)	51,000,000
Cumulative Shares Repurchased, Ending balance (in shares)	4,760,000,000
Weighted- Average Price per Share
Cumulative Weighted-Average Price per Share, Beginning balance (in dollars per share)	$ 21.30
Repurchase of common stock under the stock repurchase program, Weighted-Average Price per Share (in dollars per share)	31.80
Cumulative Weighted-Average Price per Share, Ending balance (in dollars per share)	$ 21.41
Amount Repurchased
Cumulative Amount Repurchased, Beginning balance	$ 100,303,000,000
Repurchase of common stock under the stock repurchase program, Amount Repurchased	1,620,000,000
Cumulative Amount Repurchased, Ending balance	101,923,000,000
Stock repurchase program
Class of Stock [Line Items]
Stock repurchases pending settlement	$ 0	$ 66,000,000