Investments (Realized Net Gains (Losses) Related To Available-For-Sale Investments) (Details) - USD ($) $ in Millions	12 Months Ended
Jul. 28, 2018	Jul. 29, 2017	Jul. 30, 2016
Debt Securities, Available-for-sale [Line Items]
Total	$ 287	$ (87)	$ (1)
Net gains/(losses) on investments in publicly traded equity securities
Debt Securities, Available-for-sale [Line Items]
Total	529	(45)	33
Net gains/(losses) on investments in fixed income securities
Debt Securities, Available-for-sale [Line Items]
Total	$ (242)	$ (42)	$ (34)

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.

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