Investments (Additional Information) (Details) - USD ($)	12 Months Ended
	Jul. 30, 2016	Jul. 25, 2015	Jul. 26, 2014
Investments, Debt and Equity Securities [Abstract]
Net unsettled available-for-sale investments, purchases	$ 654,000,000	$ 4,000,000
Marketable Securities, Realized Loss, Other than Temporary Impairments, Amount	3,000,000	0	$ 11,000,000
Other than temporary impairment, credit losses recognized in earnings, credit losses on debt securities held	0
Average daily balance of securities lending	$ 1,000,000,000	$ 400,000,000
Minimum market value percentage for collateral on loaned securities	102.00%	102.00%
Secured lending transactions outstanding	$ 0	$ 0