Investments (Additional Information) (Details) - USD ($)	3 Months Ended
	Oct. 24, 2015	Oct. 25, 2014	Jul. 25, 2015
Investments, Debt and Equity Securities [Abstract]
Impairment charges on available-for-sale investments	$ 0	$ 0
Other than temporary impairment, credit losses recognized in earnings, credit losses on debt securities held	0
Average daily balance of securities lending	$ 500,000,000	$ 1,000,000,000
Fair Value Of Securities Received As Collateral That Can Be Resold Or RePledged Percentage	102.00%	102.00%
Secured lending transactions outstanding	$ 0		$ 0
Cost method investment carrying value	$ 309,000,000		$ 319,000,000