Shareholders' Equity (Narrative) (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Apr. 28, 2012	Apr. 30, 2011	Apr. 28, 2012	Apr. 30, 2011
Shareholders' Equity [Abstract]
Authorized common stock repurchase amount	$ 82,000,000,000		$ 82,000,000,000
Remaining authorized repurchase amount	7,700,000,000		7,700,000,000
Cash dividends paid per common share	$ 0.08	$ 0.06	$ 0.20	$ 0.06
Cash dividends paid			1,076,000,000	329,000,000
Shares repurchased in settlement of employee tax withholding obligations			10	8
Dollar value of shares repurchased in settlement of employee tax withholding obligations			$ 160,000,000	$ 152,000,000