Investments (Gross Realized Gains And Gross Realized Losses Related To Available-For-Sale Investment) (Details) - USD ($) $ in Millions	12 Months Ended
Jul. 28, 2018	Jul. 29, 2017	Jul. 30, 2016
Investments [Abstract]
Gross realized gains	$ 628	$ 114	$ 152
Gross realized losses	(341)	(201)	(153)
Total	$ 287	$ (87)	$ (1)

This item represents the difference between the gross realized gains and losses realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. Additionally, this item would include any losses recognized for other than temporary impairments (OTTI) of the subject investments in debt and equity securities.

No definition available.

Name:	us-gaap_AvailableForSaleSecuritiesGrossRealizedGainLossNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration